Wednesday, June 30, 2004

Point of Law - Probable Cause

The Fourth Amendment to the Bill of Rights of the United States of America gave rise to the term "probable cause". In essence the Fourth Amendment carries 2 clauses. The first clause states that people have a right to be protected from unreasonable searches and seizures, and the second states that no warrant shall issue except upon probable cause.

It is widely acknowledged that the probable cause requirement is, in many ways, more important than the reasonableness clause. Not all searches and seizures require warrants. Examples of which are automobile searches and arrests in a public place. However, the US Supreme Court has interpreted warrantless searches and seizures as unreasonable unless preceded by probable cause. This means that as a general rule, most searches and seizures require probable cause.

Although there is no written definition of the term "probable cause", but generally speaking based on the established rulings from precedence, probable cause is:

(i) where known facts and circumstances, of a reasonably trustworthy nature, are sufficient to justify a man of reasonable caution or prudence in the belief that a crime has been or is being committed;
(ii) what would lead a person of reasonable caution to believe that something connected with a crime is on the premises of a person or on persons themselves; and/or
(iii) the sum total of layers of information and synthesis of what police have heard, know, or observe as trained officers.

Point of Law - Miranda Rights

The principles of Miranda Rights was founded upon the landmark case law of Miranda v. Arizona (1966). The facts of the case was that on 13 March 1963, cash of US$8 was stolen from a bank worker from Phoenix, Arizona. The police suspected and arrested Ernesto Miranda for committing the theft. During the two-hours or so of questioning, Miranda, who was never offered a lawyer, confessed not only to the US$8 theft, but also confessed to the kidnapping and raping of an 18-year-old woman just 11 days earlier. As a result, based largely on his confession, Miranda was convicted and sentenced to 20 years in jail.

Miranda's lawyers appealed all the way to the U.S. Supreme Court. On 13 June 1966, the U.S. Supreme Court, in deciding on the case reversed the Arizona Court's decision, and granted Miranda a new trial at which his prior confession could not be admitted as evidence, and thereby established the Miranda Rights of persons accused of crimes.

Although the exact wording of the Miranda Rights statements were not specified in the U.S. Supreme Court's ruling, the respective law enforcement agencies have created a basic set of simple statements that could be read to the suspects prior to any questioning. These statements are as follows:

1. You have the right to remain silent.
The U.S. Supreme Court: "At the outset, if a person in custody is to be subjected to interrogation, he must first be informed in clear and unequivocal terms that he has the right to remain silent."

2. Anything you say can be used against you in a court of law.
The U.S. Supreme Court: "The warning of the right to remain silent must be accompanied by the explanation that anything said can and will be used against the individual in court."

3. You have the right to have an attorney present now and during any future questioning.
The U.S. Supreme Court: "...the right to have counsel present at the interrogation is indispensable to the protection of the Fifth Amendment privilege under the system we delineate today. ... [Accordingly] we hold that an individual held for interrogation must be clearly informed that he has the right to consult with a lawyer and to have the lawyer with him during interrogation under the system for protecting the privilege we delineate today."

4. If you cannot afford an attorney, one will be appointed to you free of charge if you wish.
The U.S. Supreme Court: "In order fully to apprise a person interrogated of the extent of his rights under this system then, it is necessary to warn him not only that he has the right to consult with an attorney, but also that if he is indigent a lawyer will be appointed to represent him. Without this additional warning, the admonition of the right to consult with counsel would often be understood as meaning only that he can consult with a lawyer if he has one or has the funds to obtain one.

5. If you decide to answer questions now without an attorney present you will still have the right to stop answering at any time until you talk to an attorney
The U.S. Supreme Court: "If the individual states that he wants an attorney, the interrogation must cease until an attorney is present. At that time, the individual must have an opportunity to confer with the attorney and to have him present during any subsequent questioning. If the individual cannot obtain an attorney and he indicates that he wants one before speaking to police, they must respect his decision to remain silent."

The Miranda Rights, however, do not preclude a suspect from being arrested. All the police requires to legally arrest a suspect is probable cause (please kindly refer to the N.B. below), which refers to an adequate reason based on facts and events to believe that the person has in fact committed a crime. The police are however required to read to the suspect his Miranda Rights before any interrogation. Any failure to do so may ultimately cause any subsequent statements to be disregarded in court although the arrest may still be legal and valid. In addition, the police are also allowed to ask the suspect routine questions like name, address, date of birth, and social security number without reading him his Miranda Rights in an effort to establish the suspect's identity. The police can also administer alcohol and drug tests without any prior warning, although the suspect who is being tested may refuse to answer questions during the tests.

Ernesto Miranda was subsequently given a second trial at which his confession was not presented. Despite that, Miranda was again convicted of kidnapping and rape based on the evidence. He was then paroled from prison in 1972 after having served a total of 11 years. In 1976, Miranda, who was then aged 34, was stabbed to death in a fight. The police arrested a suspect who, after ironically choosing to exercise his Miranda Rights of silence, was subsequently released.

N.B. Please kindly refer to my following post "Point of Law - Probable Cause" on a more in-depth discussion on the concept of probable cause.

Tuesday, June 29, 2004

CERK Radio 40MHz - Black Wings

By the Nightcrawler Lucien Lacroix

It's Indian legend time, a Native American fairy story for children of all ages.

Legend has it that when the world was young and unfinished, the Great Spirit Father made the mistake of leaving his paints where his children could get them. Raven begged Eagle to paint him as beautiful and grand as the Great Spirit had made Eagle himself. And so he did, or so he tried. But when Raven looked at his reflection in the water, he didn't like what he saw. Raven became angry, he and Eagle fought, and the Great Spirit Father's paints were spilled over Raven and made him all black, black wings, black eyes, black breast. Raven ran into the river and flapped his wings against the current, but the color was indelible. The water wouldn't wash it away. "This is your punishment," said the Great Father, "for interfering with my work. Black you are and black you will stay. You will never come clean."

Not much of a legend at that, is it children? But I rather like the moral.

Sunday, June 27, 2004

Information Please

When I was quite young, my father had one of the first telephones in our neighbourhood. I remember well the polished old case fastened to the wall. The shiny receiver hung on the side of the box. I was too little to reach the telephone, but used to listen with fascination when my mother used to talk to it. Then I discovered that somewhere inside the wonderful device lived an amazing person - her name was "Information Please" and there was nothing she did not know. "Information Please" could supply anybody's number and the correct time.

My first personal experience with this genie-in the-bottle came one day while my mother was visiting a neighbour. Amusing myself at the tool bench in the basement, I whacked my finger with a hammer. The pain was terrible, but there didn't seem to be any reason in crying because there was no one home to give sympathy. I walked around the house sucking my throbbing finger, finally arriving at the stairway.

The telephone! Quickly, I ran for the foot stool in the parlour and dragged it to the landing. Climbing up, I unhooked the receiver in the parlour and held it to my ear.

"Information Please," I said into the mouthpiece just above my head. A click or two and a small clear voice spoke into my ear.


"I hurt my finger..." I wailed into the phone. The tears came readily enough now that I had an audience.

"Isn't your mother home?" came the question. "Nobody's home but me." I blubbered.

"Are you bleeding?" the voice asked. "No," I replied. "I hit my finger with the hammer and it hurts."

"Can you open your icebox?" she asked. I said I could.

"Then chip off a little piece of ice and hold it to your finger," said the voice.

After that, I called "Information Please" for everything. I asked her for help with my geography and she told me where Philadelphia was. She helped me with my math. She told me my pet chipmunk, that I had caught in the park just the day before, would eat fruit and nuts.

Then, there was the time Petey, our pet canary died. I called "Information Please" and told her the sad story. She listened, then said the usual things grown-ups say to soothe a child. But I was unconsoled. I asked her, "Why is it that birds should sing so
beautifully and bring joy to all families, only to end up as a heap of feathers on the bottom of a cage?"

She must have sensed my deep concern, for she said quietly, "Paul, always remember that there are other worlds to sing in."

Somehow I felt better.

Another day I was on the telephone. "Information Please."

"Information," said the now familiar voice. "How do you spell fix?" I asked. All this took place in a small town in the Pacific Northwest.

When I was 9 years old, we moved across the country to Boston. I missed my friend very much.

"Information Please" belonged in that old wooden box back home, and I somehow never thought of trying the tall, shiny new phone that sat on the table in the hall.

As I grew into my teens, the memories of those childhood conversations never really left me. Often, in moments of doubt and perplexity I would recall the serene sense of security I had then. I appreciated now how patient, understanding, and kind she was to
have spent her time on a little boy.

A few years later, on my way west to college, my plane put down in Seattle. I had about half an hour or so between planes. I spent 15 minutes or so on the phone with my sister, who lived there now. Then without thinking what I was doing, I dialled my hometown operator and said, "Information, Please." Miraculously, I heard the small, clear voice I knew so well, "Information."

I hadn't planned this but I heard myself saying, "Could you please tell me how to spell fix?"

There was a long pause. Then came the soft spoken answer, "I guess your finger must have healed by now."

I laughed. "So it's really still you," I said. "I wonder if you have any idea how much you meant to me during that time."

"I wonder", she said, "if you know how much your calls meant to me. I never had any children, and I used to look forward to your calls."

I told her how often I had thought of her over the years and I asked if I could call her again when I came back to visit my sister.

"Please do," she said. "Just ask for Sally." Three months later I was back in Seattle. A different voice answered "Information."

I asked for Sally. "Are you a friend?" She said. "Yes, a very old friend," I answered. "I'm sorry to have to tell you this, she said. Sally had been working part-time the last few years because she was sick. She died five weeks ago."

Before I could hang up she said, "Wait a minute. Did you say your name was Paul?"


"Well, Sally left a message for you. She wrote it down in case you called.

Let me read it to you." The note said, "Tell him I still say there are other worlds to sing in. He'll know what I mean."

I thanked her and hung up. I knew what Sally meant.

Friday, June 25, 2004

Point of Law - The Slippery Slope

The slippery slope argument is a logical fallacy in which a person asserts that some resultant event must inevitably happen from the occurance of a triggering event without any form of argument for the inevitability of the resultant event in question. Generally speaking, the triggering event normally comes in the form of exceptions to a rule, or rules that depend on fine distinctions. The flow of the argument says that if a person makes any exceptions to a rule, or if the person makes rules that depend on fine distinctions, the inevitable result would then be all of the other people will end up ignoring the rule or rules entirely simply because it is inevitable that they won't accept the difference between the exception and everything else. In other words, if the person allows any exceptions to a rule, it will create a slope away from the absoluteness of the rule, and with which the people will slide down further and further until they will not obey the rule at all. This fallacy is also known as the camel's nose. This follows the phenomenon that if a camel is allowed to put its nose into a tent, the whole camel will ultimately be in the tent very soon.

In most cases, there is a series of progressions between the resultant event and the triggering event and no logical reasons are generally given as to why the intervening progressions will simply be bypassed. This argument flows in the following manner:
1) Event A has occurred (or will or might occur).
2) Therefore event B will inevitably happen.
This above reasoning is fallacious because there is no reason to believe that event B must inevitably follow from event A without an argument for such a claim. This is especially clear in cases in which there is a significant number of progressions between the resultant event and the triggering event. There is old english rhyme which originated for the purpose of encouraging children to apply so-called logical progression to the consequences of their actions. The rhyme is often used to gently chastise a child whilst explaining the possible events that may follow a thoughtless act. However, when applied to the slippery slope argument, the rhyme happens to illustrate the fallacy fairly well too.

For want of a nail
For want of a nail, the shoe was lost.
For want of a shoe, the horse was lost.
For want of a horse, the rider was lost.
For want of a rider, the battle was lost.
For want of a battle, the kingdom was lost.
And all for the want of a horseshoe nail.

Generally speaking again, the presumption behind the slippery slope argument is that if the person makes any exceptions to a rule, the other people will think that the rule is arbitrary to begin with and will see no reason to follow it at all. Hence, any exceptions undermine respect for a rule, and thus eventually lead to the rule's not being followed at all. Another argument is that people generally cannot make fine distinctions, so if you make an exception to a rule, the other people will think the person has shown the rule to be flawed and therefore unnecessary to follow.

N.B. I have previously used the english rhyme "For want of a nail" to illustrate the butterfly effect (please kindly refer to my previous post "The Butterfly Effect"). Come to think of it, the Butterfly Effect and the Slippery Slope Argument seem to run in the same direction.

Thursday, June 24, 2004

The Butterfly Effect

Predictability: Does the flap of a butterfly’s wings in Brazil set off a tornado in Texas?

The butterfly effect technically refers to the propensity of a system to be sensitive to initial conditions. It is the sensitive dependency on its initial conditions that the system, over time, becomes wholly unpredictable.

The butterfly effect is however not quite as similiar as the domino effect. For the domino effect, there is no doubt dependency of the system on the initial conditions. But a simple linear row of dominoes would merely allow one event to initiate another similar event upon each iteration. The butterfly effect however amplifies the condition upon each iteration.

The butterfly effect has been most commonly associated with the weather system as this is where the discovery of non-linear phenomenon within a complex and dynamic system began. Due to nonlinearities in the weather processes, a butterfly flapping its wings in Brazil can, in theory, produce a tornado in Texas. This strong dependence of outcomes on very slightly differing initial conditions is a distinct characteristic of the mathematical behavior known as chaos. The idea in meteorology that the flapping of a butterfly's wing will create a disturbance that in the chaotic motion of the atmosphere will become amplified eventually to change the large scale atmospheric motion, so that the long term behavior becomes impossible to forecast.

Flowing from the above argument, the butterfly effect in fact represents the essence of chaos. A complex and dynamical system is deemed to be chaotic if it
1. Has a dense collection of members with periodic orbits,
2. Is sensitive to the initial condition of the system (so that initially nearby members can evolve quickly into very different states), and
3. Is topologically transitive.
Chaotic systems exhibit irregular, unpredictable behavior. The boundary between linear and chaotic behavior is often characterized by periodic doubling in orbits, followed by quadrupling in orbits etc., although other kinds of combinations are also possible.

Animal populations are also subjected to the same phenomenon. Empirical evidence suggests that predator-prey systems too have complex dynamics making them prone to cycles. Such a system even with two simple variables such as rabbits and foxes can create a system that is really much more complex than initially thought to be. The lack of foxes may mean that the rabbit population can increase initially. But the increasing numbers of rabbits may also mean that the foxes have more food and are therefore more likely to survive and reproduce, which then in turn decreases the number of rabbits. It is possible for such systems to find a state of equilibrium, and even though species can become extinct, there is a tendency for populations to be robust. However, they can vary dramatically under certain circumstances. Real populations, of course having more than two variables, are even more complex than that of the illustration as given above.

The effects of the butterfly effect is best demonstrated by the Lorenz Attractor. The Lorenz Attractor is a graphical representation of the time variation of three variables coupled by non-linear evolution equations. You will observe that for the two separate non-linear evolution equations that are made to run simultaneously from slightly differing initial conditions, the tiny difference in the initial conditions becomes amplified by the evolution, until such time the two trajectories evolve quite separately. The amplification is exponential, the difference grows very rapidly and after a surprisingly short time the two solutions behave quite differently.

After having explained the butterfly effect from the scientific angle, it may also be appropriate to examine it from the layman's angle. There is a clever set of lyrics that is derived from an old english rhyme which originated for the purpose of encouraging children to apply logical progression to the consequences of their actions. The rhyme is often used to gently chastise a child whilst explaining the possible events that may follow a thoughtless act. But in this case, it perfectly explains the butterfly effect.

For want of a nail
For want of a nail, the shoe was lost.
For want of a shoe, the horse was lost.
For want of a horse, the rider was lost.
For want of a rider, the battle was lost.
For want of a battle, the kingdom was lost.
And all for the want of a horseshoe nail.

Wednesday, June 23, 2004







N.B. 这歌中的词是我所读过当中最有凄美感的一个.


By Terry Bisson

Imagine if you will... the leader of the fifth invader force speaking to the commander in chief...

"They're made out of meat."


"Meat. They're made out of meat."


"There's no doubt about it. We picked several from different parts of the planet, took them aboard our recon vessels, probed them all the way through. They're completely meat."

"That's impossible. What about the radio signals? The messages to the stars?"

"They use the radio waves to talk, but the signals don't come from them. The signals come from machines."

"So who made the fucking machines? That's who we want to contact."

"They made the machines. That's what I'm trying to tell you. Meat made the machines."

"That's bullshit. How can meat make a machine? You're asking me to believe in sentient meat."

"I'm not asking you, I'm telling you. These creatures are the only sentient race in the sector and they're made out of meat."

"Maybe they're like the Orfolei. You know, a carbon-based intelligence that goes through a meat stage."

"Nope. They're born meat and they die meat. We studied them for several of their life spans, which didn't take too long. Do you have any idea the life span of meat?"

"Spare me. Okay, maybe they're only part meat. You know, like the Weddilei. A meat head with an electron plasma brain inside."

"Nope. We thought of that, since they do have meat heads like the Weddilei. But I told you, we probed them. They're meat all the way through."

"No brain?"

"Oh, there is a brain all right. It's just that the brain is made out of meat!"

"So... what does the thinking?"

"You're not understanding, are you? The brain does the thinking. The meat."

"Thinking meat! You're asking me to believe in thinking fucking meat!"

"Yes, thinking meat! Conscious meat! Loving meat. Dreaming meat. The meat is the whole deal! Are you getting the picture?"

"Oh shit. You're serious then. They're made out of meat."

"Finally, Yes. They are indeed made out meat. And they've been trying to get in touch with us for almost a hundred of their years."

"So what does the meat have in mind?"

"First it wants to talk to us. Then I imagine it wants to explore the universe, contact other sentients, swap ideas and information. The usual."

"Fuck that. We're supposed to talk to meat?"

"That's the idea. That's the message they're sending out by radio. 'Hello. Anyone out there? Anyone home?' That sort of thing."

"They actually do talk, then. They use words, ideas, concepts?"

"Oh, yes. Except they do it with meat."

"I thought you just told me they used radio."

"They do, but what do you think is on the radio? Meat sounds. You know how when you slap or flap meat it makes a noise? They talk by flapping their meat at each other. They can even sing by squirting air through their meat."

"That's disgusting. Singing meat. This is altogether too much. So what do you advise?"

"Officially or unofficially?"


"Officially, we are required to contact, welcome, and log in any and all sentient races or multibeings in the quadrant, without prejudice, fear, or favor. Unofficially, I advise that we erase the records and forget the whole fucking thing."

"I was hoping you would say that."

"It seems harsh, but there is a limit. Do we really want to make contact with meat?"

"I agree one hundred percent. What's there to say?" `Hello, meat. How's it going?' But will this work? How many planets are we dealing with here?"

"Just one. They can travel to other planets in special meat containers, but they can't live on them. And being meat, they only travel through C space. Which limits them to the speed of light and makes the possibility of their ever making contact pretty slim. Infinitesimal, in fact."

"So we just pretend there's no one home in the universe."

"That's it."

"Cruel. But you said it yourself, who wants to meet meat? And the ones who have been aboard our vessels, the ones you have probed? You're sure they won't remember?"

"They'll be considered crackpots if they do. We went into their heads and smoothed out their meat so that we're just a dream to them."

"A dream to meat! How strangely appropriate, that we should be meat's dream."

"And we can mark this sector unoccupied."

"Good. Agreed, officially and unofficially. Case closed. Any others? Anyone interesting on that side of the galaxy?"

"Yes, a rather shy but sweet hydrogen core cluster intelligence in a class nine star in G445 zone. Was in contact two galactic rotations ago, wants to be friendly again."

"They always come around."

"And why not? Imagine how unbearably, how unutterably cold the universe would be if one were all alone."

CERK Radio 40Mhz - Blood Money

By the Nightcrawler Lucien Lacroix

It is said that nature will not tolerate excess, as in the case of those who take more than their fair share. They're dealt with accordingly. For when you have too much, there will always be someone wanting to take it away from you. So maybe you should ask yourself, has your blood money been a blessing or a curse?

Tuesday, June 22, 2004

Random Thoughts - Separation of the Church and State

By some ants in B.C. by Johnny Hart

Define the separation of the church and state:

The concept whereby a clergyman has as much chance to be becoming a president as a lawyer has of becoming a pope.

Random Thoughts - Markers

Do you remember the time when you were still a small child, and your perspective of the world at large was still relatively unrefined? Do you remember the time when everything in your world appeared to be either longer or larger than they really were, or at least when compared to your current perspective now? Well, I recently recalled some events from my past in relation to the above questions while reading an article. These recollections led me to come to the same conclusions as the author of the article. And subject to my usual long windedness stuff, I am pleased to share my sudden revelation with you.

While I was still in primary school, my parents used to take my brother and myself to the 2 cinemas along Balestiar Road, being the President and the Hoover I think, to watch movies. To me at least, those car trips to the cinemas were really much too long for anyone my age at that time to take. At that point in time, I was living in a 5 room flat along Bendemeer Road, and the time needed to cover the distance between Bendemeer Road and Balestiar Road could not have been more than 15 minutes. But to me, they were like forever.

As such, I instinctively devised some things to do along the way to the cinemas. My favorite pastime would have to be the counting of road signs, buildings and traffic lights, which we passed along the way. Sometimes, I would even count the dashes of the lane dividers. I would not recommend this exercise to anyone rational as this exercise was a highly stressful and tiring activity, and its success really depends critically on the speed at which the car is moving. Heavy traffic is certainly helpful in this aspect but in general it really just prolongs the pain of getting to the destination. I would certainly not be proud to report to you that there are a total of four hundred and fifty three dashes between the cross junctions of Bendemeer Road / Geylang Bahru and Balestiar Road / Moulmeim Road and I am not saying that there actually are, but please do feel free to verify the number for yourselves if your interested in this sort of activities.

Today, in retrospect, I realised that I only did what I did then because those activities actually helped me pass time more quickly in a very relative sense. I have instinctively forced myself to notice and to keep track of the road signs, buildings, traffic lights and the dashes of the lane dividers. In the process, I have created what the author called a series of “markers” to measure the time and distance taken to move from place to place. As a result, I would then know, at any given point, what places we have just passed and what places we would be coming to next before reaching the destination. These markers really served to provide the mind with an alternate means of measuring time and space and allow the mind to gauge the percentage of completion of the task at hand. And, this markers, through occupying the mind, give time the appearance of passing more quickly than they really are, relatively speaking of course.

Interestingly, I was discussing some conceptual issues involving the MRT along the north east line with a friend the other day where I suddenly realised that I do not refer to the MRT stops by their designated names but rather their designated numbers. For example, I do not refer to the MRT stop at Toa Payoh as Toa Payoh but as N6. I was at first bewildered at my apparently strange behaviour since I have always prided myself as a word person rather than a number person. On deeper analysis, perhaps instinctively, I have used the designated numbers as a means to measure the progress of my journey via the MRT for the same reasons why I counted the road signs, buildings, traffic lights and the dashes of the lane dividers in my younger days. If you will, please imagine yourself riding the MRT through an underground tunnel between 2 stops. I suspect that the ride would appear to take longer than it really did simply because there are no markers along the underground tunnel for the mind to take reference from. But imagine riding the MRT for the same distance on the surface where we can see the world where there are markers along the way. The impression created may be quite different from the previous.

I particular liked the statement that was made by the author in relation to his commentary on markers. I concur with his comments in its entirety. He said: ”Funny how when you are young you instinctively know and understand such things; then you forget them and only years later do you relearn, through curiosity and inquiry and chance, what was once instinctual. What a shame that this is the way of life”.



剑是心, 心是剑.
心有法, 而剑无为.

剑在人心之中, 随而心剑而一,
人就是剑, 剑也是人,

剑应因意而生, 因意而动.

Crime Scene Investigation - Detection of Latent Prints

Latent prints are the kind of finger prints found at crime scenes which are formed by the oil and sweat secretions deposited by a person's fingers when they touch a surface or an object. They are invisible to the naked eye and need some kind of treatment to make them visible.

The most widely used method of detecting latent prints is to dust using a fine powder that adheres to the traces of oil and sweat. Dusting is suitable for hard and/or non-absorbent surfaces. There any many different kinds of powder in use today. For example;
aluminium dust, which is grey and highly visible on dark and mirrored surfaces;
carbon black for white surfaces; and
luminescent powders which fluoresce under ultraviolet light.

N.B. A common every day application of luminescence is washing powder that contains optical brightener. The optical brightener is nothing more than a fluorescent dye that shows a blue luminescence when excited by the ultraviolet radiation present in sunlight. The optical brightener is added to counteract the yellowing of cotton as it ages.

For porous surfaces like paper or cloth, a number of methods have been developed over the years to help detect fingerprints. Examples are as follows:

Iodine fuming
This is the oldest of the chemical methods for detecting fingerprints. Solid iodine sublimes (becomes a vapour without becoming a liquid) at room temperature. If an object, say a piece of paper, is placed in a chamber which a has had some crystals of iodine placed in it, any fingerprints on the object will appear as brownish prints. What is thought to be happening is that the iodine vapour is dissolving in the skin oils (or may be the traces of water from the perspiration) that make up the print. Whatever is happening the print is temporary and will soon fade. It must therefore either be photographed immediately or "fixed" by spraying with starch solution to give a blue print which will last longer.

Iodine fuming has to a great extent replaced by other methods including spraying with the chemical ninhydrin which reacts with amino acids present in the skin secretions to give purple prints.

The active ingredient in superglues is a cyanoacrylate ester. When vapours of these compounds come into contact with fingerprints the molecules of the cyanoacrylate attach to the print and polymerise. The visible prints produced are white, to improve their detectability they are often treated with a fluorescent dye, such as Rhodamine 6G, before being photographed under an special light source or a laser.

Luminescence and Fingerprinting
Some molecules when irradiated with certain types of light fluoresce, the phenomenon is called luminescence. Researchers discovered some years ago that some components of sweat are luminescent and fluoresce when illuminated with lasers. There are disadvantages in using lasers as they are expensive and there are significant safety issues to consider. With the advent of treatment of fingerprints with fluorescent dyes (see above), the use of so-called alternate light sources which are essentially high intensity lights has increased as they are less expensive, safer and more portable than lasers.

Crime Scene Investigation - Luminol Test

Blood and other bodily fluids which are found at the crime scene may give important physical evidence in three ways;
1)The occurrence of a blood strain in a certain place, e.g. on a weapon may substantiate an account of a crime;
2)The shape, position, size or intensity of a bloodstain may support a particular sequence of events; and/or
3)The blood typing analysis can be used to eliminate whole groups of people as suspects.
It is therefore important to be able to identify a particular stain as blood or not, or maybe even to reveal "hidden" bloodstains on dark materials or where attempts have been made to wash the blood away.

Human blood contains a pigment called haemoglobin, which is used to transport oxygen around the body. This pigment is used by a number of tests to identify the presence of blood. One particular test that reveals the presence of blood is the Luminol Test. In this test the bloodstains can be made to glow with a blue light due to the chemiluminescent reaction of the luminol reagent with the iron in the haemoglobin.This test is sensitive enough to pick up minute traces of blood even when attempts have been made to wash away the incriminating evidence.