Fake DNA Evidence
- First I googled DNA Profiling to find out how forensic scientists use DNA to catch criminals.
- This took to me en.wikipedia.org/wiki/DNA_profiling
- DNA profiling is a technique used my forensic scientists. There are a variety of ways they can use DNA. However, PCR and STR are the most common of way because they're the most reliable.
- STR (Short Tandem Repeats)-Scientists study certain repeated sequences of DNA. Everyone has different repeats in their DNA so it's easier to find the person committing the crime.
- PCR (Polymerase Chain Reaction)- Replicates DNA to make more of it. You need more than just a few samples of DNA which they collect from a crime scene. This helps them make more copies to look at it.
- I scrolled down on the same page and found a headline that read "Fake DNA Evidence."
- I found the name "John Schneeburger" I found his case to be very unique so I decided to google him.
- I clicked the link reportingpoint.net/538081c1a7585b28.html
Step 3: John Schneeberger
- John was a physician who practiced in Kipling, Saskatchewan. On October 31, 1992, he sedated his patient, Candice. He then raped her. However, when she awoke, she was able to remember the incident. She reported the rape to the police. When they took DNA evidence from John, it didn't match the rapists semen. Candice, knowing he did it, requested another blood sample in 1993. Again. the result was negative. the case was closed in 1994.
- Candice hired a private investigator. The investigator broke into Schneeberger's car and obtained some DNA samples. These matched the semen that was found. However, when they tested John's blood again, the sample was too small and too poor of quality to be useful.
- In 1997, his wife found out that he had drugged and raped their daughter. When she reported ti to the police, they took hair, saliva, and blood samples. All three matched the semens DNA.
- In the 1999 trial, Schneeberger admitted to inserting a Penrose drain (Surgical divide to drain fluid) filled with another patients blood and anticoagulant (substance that prevents blood clotting) into his arm. When asked to give a blood sample, he simply offered the arm that had the tube in it. Rather than the needle going into the vein, it went into the tube.
- Schneeberger was sentenced six years but only served four before being deported to South Africa.
- John's case, although interesting, I realized didn't have much to do with the DNA part of DNA profiling. I decided to go back and google "Fake DNA Evidence"
- Israeli scientists who work for a company called Nucleix have found two different ways DNA evidence can be faked.
- They can use samples of DNA evidence from law enforcement databases, which record 13 different places on a person's DNA, and use it to create a DNA genome that matches that of the suspect or another person.
- They can take a sample of the person's DNA that is to be faked.
- In both cases, the DNA is amplified (PCR) and inserted into red blood cells which can be seen as true DNA.
- However, there are some ways you can identify if the DNA is being faked.
- A normal sample will contain both red and white blood cells but these fake samples will only contain red blood cells.
- The fake samples will lack a specific molecule that is only found in normal DNA.
- I went back and clicked on another link to see if i could find out how they came up with their findings.
- They cloned tiny DNA snippets from the DNA samples they took from law enforcement and mixed the proper snippets together to create a DNA sample that matched the one they wanted it too. They also found you only need about 425 different samples to cover every human profile.
- The scientists took blood from a woman and centrifuged it to remove all of the white blood cells (which contain the DNA). Then, they added DNA that had been amplified form a mans hair follicle into the red blood cells. Since red blood cells don't contain DNA, when the sample was looked at, all of the DNA matched that of the man's even though the women's blood cells were being used.
- I also found that the molecule that fake DNA lacks is called methylation.