Murder case | Forensic DNA samples tested

12 Aug 2017

Murder cases systematically rely on finding and testing DNA samples to indentify victims and link alleged the perpetrators to the crime scene and their victims. Significantly, the accuracy and advances in the field  of DNA testing means that forensic DNA samples are now used by genetic testing companies to do paternity DNA tests and other types of DNA tests in a way that is analogous to how it is collected and analyzed in crime scene.

The Triple Murder

Janesville, Wisconsin, USA, a triple murder case is being solved thanks to the forensic experts who have found a number of forensic DNA samples to support the case. James Koepp, the alleged murder, is accused of having murdered Danyetta Lentz and her two young children, 14 year old Scott and his older sister, Nicole, 17. Lentz’s father was the one to walk into the horrid scene the day after the murder of his daughter and her children took place.

DNA testing of forensic evidence is central to the case. Blood stains where found on the James’ jeans and the DNA expert in charge of the case, Daniel Campbell, claims that the statistical probability of the DNA found not belonging to the victim is 1 in 7 quadrillion. The DNA profile of Danyetta and that found on the alleged murderer’s jeans is the same. This incontrovertible evidence means that the defense has to build up a solid case to convince the jury of his innocence in the final hearing that is shortly to come.

Forensic DNA expert teams have found a number of useful sources of DNA including finger nails, a tie that was used to strangle the victim, blood and even a body scrubber. These sources are all potentially useful to solve the case. They can help establish who committed the murder, who was on the crime scene and link the murderer to his victims.

The defense has to disprove the solid forensic DNA evidence gathered. In fact, they claim the family’s mobile home had been broken into prior to James arriving on the crime scene.  The defense claims that the intruders are the one who killed that family of three. However, they need to build up a stronger case if they wish to convince the jury in the final trial that Koepp is innocent of the crime.

The use of Forensic Samples in DNA Testing

Forensic samples can be used to carry out a number of tests including paternity DNA tests, infidelity tests and relationship DNA tests. This means that forensic DNA testing is now carried out in just the same way as forensic experts do on a crime scene using a multitude of samples that can all potentially provide DNA. Most DNA testing companies refer to forensic samples as forensic DNA samples and are often used when a participant in the test in unavailable for testing. There are however, certain laws in some countries limiting how one uses DNA samples and you may want to consult the company of your choice before you go ahead with purchasing your test.

You may want to do a paternity DNA test and need a sample from the father but do not wish him to be aware that he is being tested for paternity. In this case, you may perhaps send in a Kleenex that he may have used to be tested to create his DNA profile and compared to that of the child.

With every forensic sample there is what is referred to as a ‘success rate’ which is specific to each sample. By ‘success rate’ we mean the likelihood of the laboratory extracting enough DNA from the sample in order to finish the test. Some samples have a low probability of extracting DNA and some a very high one.