What happened to Vithya’s DNA evidence?


In May of 2015, an 18 year old Vithya Sivaloganathan’s badly mangled body was discovered in Pungudutivu, Jaffna. She had been gang raped and murdered.

The result of the DNA sample taken from her body has not yet been analyzed.

Last month, September, four year old Seya Sadewmi’s mutilated little body was discovered, she too had been raped and murdered.
Of the three suspects arrested in connection with this murder, two were released after DNA evidence taken from the victim’s body did not match, DNA evidence from the suspects.

The Genetech Molecular Diagnostics is a private organization which is Sri Lanka’s only method to pave the way for DNA testing. This organization is currently in charge of analyzing both aforementioned cases in addition to over 4,000 criminal cases that they have handled over the past 12 years.
“These two cases were somewhat similar because the victims are young female individuals, raped and murdered. So the samples that we had to take were more or less the same. When a female is sexually assaulted, biological evidence is recovered from the vagina of the victim. The intention of taking that type of a sample is to isolate traces of semen found inside the body of the victim left behind by the perpetrator.”

Speaking to Ceylon Today, senior scientist and Head of molecular forensics at the Genetech Molecular Diagnostics Dr. Ruwan J. Illeperuma Ph.D. said that in Vithya’s case, the DNA evidence was quite difficult to analyse as it was a mixture of DNA from multiple perpetrators.

“When a female is sexually assaulted or raped, biological evidence is recovered from the vagina of the victim. The intention of taking that type of a sample is to isolate trace of semen left behind by the perpetrator inside the body of the victim,” he said adding, “It has not been fully tested as of yet, because the DNA analysis is still ongoing. Before we get into any conclusion we have to compare this DNA information with the DNA information of the suspects. It has not yet been done. So we still have not been able to come to a conclusion.”

“Gang rape in particular, if our main DNA evidence is semen from the vagina of the victim, it would end up with multiple DNA profiles because of the presence of multiple samples from several different male individuals. So there is no way in science to easily separate DNA fragments from these multiple individuals. That is called a mixed DNA profile. Normally such a profile will make it hard for a scientist to separate them,” he said further adding, “However, for a scientist who has a good knowledge and experience to interpret DNA information by using a mixed DNA profile it is not impossible. So even if Vidya’s case does have a multiple semen sample, originated from multiple individuals, and it will surely end up with a mixed profile, we can interpret it. The comparison of multiple samples is statistical interpretation not a pure science based interpretation.”

Furthermore, Dr. Illeperuma added that the specific government officers have not provided Genetech with a full set of samples from Vithya’s case.

“In Seya’s case we are analysing several samples but in Vithya’s case we initially did not get the full set of samples. However, I cannot explain what I mean by a full set of samples because the case investigation is still under way, and the Court has informed us to perform DNA testing from some of the samples. A set of samples are currently being tested by the Government Analyst while the other set is under my responsibility.”

A 17 year old school boy and a 33 year old father of one were initially arrested on suspicion of the rape and murder of Seya Sadewmi. However, after DNA evidence from Genetech proved that the samples taken from Seya’s body did not match either suspect, they were released last Thursday (01).
“In Seya’s case we have made a conclusion that there are no detectable amounts of DNA of these two suspects from the male DNA component which we took from the victim. However, the decision that they were not the ones who committed the crime is not up to us to decide. Our duty is to confirm whether the suspect’s DNA was present in the body of the victim.”

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