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Forensic science - real cases


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  • Elders (Admins)

Here are some cases where advances in forensic science have been crucial in bringing cases before the court that otherwise couldn't have been prosecuted:

A medical doctor, Richard Schmidt, injected Janice Trahan, a nurse with whom he'd been having an affair, with both HIV and Hepatitis C under the guise of vitamin injections. When Ms Trahan was diagnosed, investigation of her previous blood tests gave an indication as to when she became infected. Examination of the doctor's records for the relevant time (which he had hidden) showed that one blood sample, of a known HIV patient of his, did not have a tracking record – indicating that it had not been sent on for routine testing. Could this be the source of Ms Trahan's HIV?

However, there was a problem. Two samples of human DNA can be matched, but the DNA in HIV, as is the case of most viruses, changes rapidly. So doing a direct comparison between Ms Trahan's HIV and the patient's wouldn't help. But a researcher, Michael Metzker of Baylor College of Medicine, provided a mechanism for comparison. Viruses do rapidly mutate once they enter the body, but if the infection is from the same source, they mutate in much the same way. Metzker analysed the mutations and found similarities in both samples.

That gave credence to Ms Trahan's allegations, except that the patient didn't have Hepatitis C. A further examination of Schmidt's (hidden) records showed a second patient whose blood sample also didn't have a tracking record, and that patient had Hepatitis C.

This case was the first time that HIV mutations became part of the forensic evidence put forward in a prosecution. Michael Metzker was a graduate student at the time of his discovery of this technique.

Schmidt was found guilty of attempted murder and was sentenced to 50 years imprisonment.

Marleen Major disappeared under strange circumstances. One year later, a human skull was found not far away. It was absent the lower jaw, and the teeth in the upper jaw had been removed, so dental records could not be used for identification. And the skull was too degraded for DNA sampling as it was available at that time.

Some twenty years later, Marleen's daughter, Lalana, set out to discover what had happened to her mother. This was a painful journey as her father had been convicted of sexually abusing her and her brother. By then a new technique had been discovered of comparing mitochondrial DNA, which is passed down from the mother only to her children. Comparing the mitochondrial DNA in the skull with Lalana's showed that the skull was that of her mother. Subsequently her father confessed to the murder and was sentenced to life imprisonment.

No further remains of Marleen were found.

A couple, Clifford and Alma Merck, had been found dead in their ransacked home. Clifford had been shot. An examination of the retrieved bullet indicated the type of gun that was used, which was the same as Clifford's own gun but which was missing. Police checked every gun of that type, but the rifling couldn't be matched. Jewellery was also missing from the house and investigators made a connection between a well-known fence and two brothers who were also well known to the police. A gun was retrieved which was identified as Clifford's, but again the rifling didn't match. Ten years later, the case was reopened. By then, investigators knew that a technique which was frequently used by fences was to insert a screwdriver down the barrel and thereby override the original rifling pattern. Since any bullet fired from that gun would adopt the different rifling pattern, that would be of no use for forensics. But one forensic scientist had the idea of using the same materials as used in taking dental impressions and obtaining the rifling pattern in the barrel from the trigger end, where the screwdriver hadn't reached. That showed an identical pattern between the gun and the bullet that killed Clifford.

That was the first time that this technique had been used.

Subsequently, one of the brothers was release because there was no forensic evidence linking him to the crime, but the other brother, Robert Cowan, was found guilty of two counts of first degree murder and sentenced to death.

Those cases occurred in the USA. This last one happened in the UK, and it's different because there was no ground-breaking forensic science involved, only a case of people not asking the right questions.

Maria Marchese had been stalking her victim for a very long time. Initially, the police were not much interested until death threats were issued. Because of the severity of those death threats, issued against both the victim and his then fiancée, including a threat to burn the fiancée in her wedding dress, a "sting" was set up at the couple's aborted wedding to identify the perpetrator. The perpetrator was discovered to be Maria Marchese. She was arrested and dealt with, but continued her harassment. The relationship between the victim and his fiancée broke down because of the stress.

Sometime later, Marchese alleged that her victim had raped her years earlier, and produced underwear she had kept. Forensic examination of the clothing showed DNA of both Marchese and her victim, which is what needed to be proved. The victim was then arrested, charged with rape, and bailed.

More than a year later, the charges of rape were dropped shortly before the trial because the victim's lawyers had arranged their own forensic examination and that showed that there was DNA of three people on the underwear that Marchese produced. That included Marchese, the victim, and the victim's new girlfriend. That made no sense given when the rape was supposed to have happened, but could only be explained by Marchese going through the victim's rubbish bin and finding a used condom which she used to contaminate her own unwashed underwear, but inadvertently she also deposited DNA from the victim's new girlfriend.

Marchese was sentenced to nine years imprisonment. There are different sentencing practices in the UK as opposed to the USA. In the UK, nine years for this kind of stalking is almost unprecedented.


"Humans need fantasy to be human. To be the place where the falling angel meets the rising ape." Terry Pratchett

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Reminds me of a few quotes from Criminal Minds, one of my favorite shows.

]"Murder is unique in that it abolishes the party it injures, so that society must take the place of the victim, and on his behalf demand atonement or grant forgiveness." W.H. Auden

"Of all the animals, man is the only one that is cruel." Mark Twain

"Wild animals never kill for sport. Man is the only one to whom the torture and death of his fellow creatures is amusing in itself." James Anthony Froud

"Tragedy is a tool for the living to gain wisdom, not a guide by which to live." Robert Kennedy

"Nothing is easier than to denounce the evil doer; Nothing more difficult than understanding him." Fyodor Dostoevsky


"Time is too slow for those who wait; too swift for those who fear;

too long for  those who grieve; too short for those who rejoice.

But for those who love, time is eternity."

(Jane Fellowes)

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