Law enforcement authorities have come a long ways from Sherlock Holmes when the powers of deduction and observation were the essential requirements to solve the mystery of a crime. Forensic investigations cover a range of activities including determining time of death, cause of death, analysis of blood, hair, fingerprint, and DNA samples collected from the crime scene to identify the person(s) at the crime scene.
Crime writers draw upon forensic techniques in solving a mystery. The craft of writing is to have the scientific elements well integrated into the story. Long technical passages about the science behind the techniques are boring for most readers who are interested in the human element.
It would be a mistake not to take into account up-to-date forensic techniques in a crime novel set in contemporary times. Such attention to detail indicates the writer has done his/her research by portraying modern law enforcement practice as aids to unraveling the mystery of who committed the crime. Also evidence gathered by forensic teams may be crucial to securing a conviction. Evidence at a crime scene is vulnerable to contamination. In Thailand, it is not uncommon to find onlookers, reporters, neighbors mixing with police inside a crime scene. Once the crime is disturbed by the presence of others, the evidence of the actual suspect can be difficult to locate.
In the last few years, new scientific developments have equipped forensic officials with more powerful tools to extract and analyze evidence found at a crime scene. Modern forensic techniques allow the police and prosecutors a more detailed, accurate and reliable basis to connect a suspect with a crime.
There are a couple of lipstick smudges found at a crime scene. The lipstick is red. It could have come from any number of brands. It’s like finding a boiled egg, which could have been laid by any number of hens. Narrowing down the scale of red lipstick might be helpful in an investigation. One way of isolating the red lipstick is to establish its brand. Once the brand can be established this information is helpful in identification issues when a victim and suspect have had physical contact. The suspect says the lipstick is his girlfriend’s or wife’s, but the match on the victim’s cigarette butt is the same brand as the one found at the crime scene.
In England, forensic experts have devised a technique called Raman spectroscopy. The device uses a laser light to establish the brand. Apparently each brand has a vibrational fingerprint that establishes its identity. Lipsticks fall along what is called a Raman spectrum—and each type and brand falls at some point in the spectrum. The crime scene sample might be from any number of items such as drinking glasses, a napkin, a shirt collar, or a piece of wadded tissue. One of the advantages of the new lab techniques is the lipstick sample isn’t destroyed in the process to determine the brand. Indeed the Raman spectroscopy allows the lipstick sample to remain in the sealed crime scene evidence bag.
On the horizon look for a similar technique to identify the brand of eyeliners, skin creams, and powders.
Taking fingerprints from a crime scene has been common for nearly a century. We have in our mind TV images of forensic teams arriving at a crime scene to gather clues. Sherlock Holmes would have studied the fingerprint with a large magnifying glass to see if the ridges, loops and whorls matched those of the victim and suspect. The stage of analysis is running the fingerprints through a large national database.
If there is a match, the investigators know the identity of their suspect. The courts require a high degree of certainty before the fingerprints can be introduced as evidence in a criminal case. The issue arises when there is a partial print, a smudge print, or a print that has been degraded by weather, fire, heat, water or chemical agents.
If the authorities discover a complete fingerprint at a crime scene, they have a powerful piece of evidence. “The odds of two individuals having identical fingerprints are 64 billion to 1, making them an ideal tool for identification in criminal investigations.” Link: http://www.sciencedaily.com/releases/2013/07/130702202907.htm
Fingerprints that don’t find a database match are a problem. How do the authorities identify such a person? The forensic team may have found a ‘latent’ print at the crime scene and need a method to identify it with a suspect. Another issue is the suspect may be identified by his/her prints but claims by way of defense diminished responsibility or insanity.
We are entering a time when crime scene fingerprints tell a more complete story beyond the ridges and whorls. The more comprehensive and complete this story becomes, the higher is the probability that the fingerprint identifies the accused. The science reduces the scope of uncertainty, allowing courts to be more easily persuaded to admit the fingerprint evidence against the accused. Lastly, fingerprints from paper such as paper money have been difficult to extract.
In England, researchers have been able to analysis more than just the whorls on a fingerprints, extracting evidence of recreational drugs, prescription medicine, and diet. In other words, the lab can create a picture of the suspect’s lifestyle. This may narrow down the range of possible suspects.
Watch the fingerprint analysis data over the next few years. It is likely that scientists will be able to extract a great deal of biomedical data from a fingerprint. Those running national fingerprint database may reorganize categories to take into account specific data ‘points’ and that may allow authorities to draw correlations between the presence of certain drugs or dietary practices that increase the probability of criminal conduct. As computer software becomes faster and Big Data (assuming arrangements are made to share fingerprint databases across multiple jurisdictions) more common, it is likely the reliability of matching will become much higher.
The problem of using fingerprints on paper money has been solved by new methods. “Prof. Yossi Almog and Prof. Daniel Mandler of the Institute of Chemistry at the Hebrew University, uses an innovative chemical process to produce a negative of the fingerprint image rather than the positive image produced under current methods.” Link: http://www.sciencedaily.com/releases/2012/11/121106084901.htm
In the case of a sex crime, investigative technical advances allow investigators to determine whether the fingerprint came from someone who wore a condom. The absence of the suspect’s DNA in the body of the victim creates a reasonable doubt. However, if the suspect’s fingerprints reveal lubricant from a condom, this fact becomes evidence to explain the absence of DNA.
Collecting and analyzing crime scene evidence is on course for a major transition as testing techniques and databases increase in quality and reliability. Along with the ever present CCTV cameras, and facial recognition software, the capacity for identifying suspects in a criminal case will continue to improve. The future may see a shift from efforts to cast doubt on ‘who done it’ to what basis was the suspected motivated to commit the crime. Self-defense, drugs, alcohol, and genetic factors beyond the control of the suspect are likely to surface to justify the action or as mitigation of intentionality.