New Delhi: The CBI, investigating the
two-year-old Aarushi murder case, is likely to approach a
laboratory outside the country to extract crucial forensic
evidence from the samples collected from the scene of the
The samples including the bedsheet, blood, fingerprints,
bottles and her vaginal swab were all contaminated.
The CBI has contacted a forensic laboratory outside
India where certain samples collected from the scene of crime
will be sent in order to extract DNA from them as it would
help further investigations in the case, sources privy to the
The laboratory has the expertise for extracting DNA from
samples which are highly contaminated but have been touched by
the criminal. The technique used is called touch DNA which
means that that DNA of the person can be obtained from an
object that he has touched. It has helped solve dead-end
cases, the sources said.
When any individual touches an object he leaves behind a
print that is basically made up of oils and dirt that are
constantly deposited on his fingers.
As such everything that is touched picks up a bit of oil
and dirt which are left as fingerprint on the object. Body
cells become part of the fingerprint and it is these that are
the source of the DNA.
A single cell is enough to provide enough DNA for
analysis. So if the murderer has touched anything in the
house, his DNA profile can be chalked out even if he has used
gloves because skin cells keep on drying and falling from the
body, the sources said.
The samples that were collected from Aarushi`s house
were declared to be highly contaminated by a forensic
laboratory here. DNA evidence can become contaminated when DNA
from another source gets mixed with DNA relevant to the case.
"As such no forensic evidence could be extracted by
which we could zero in or rule out those suspected in this
murder case," he said.
"This laboratory has been chosen after visiting nearly
all websites of the foreign laboratories that have this
technique," the sources said.
Aarushi, 14-year-old daughter of a successful dentist
couple Dr Rajesh and Nupur Talwar, was found dead with her
throat slit in her parents` home at Jalvayu Vihar in Noida on
May 16, 2008. So far, the police and later the CBI failed to
even identify the murderer.