HARRIS COUNTY, Texas – Channel 2 Investigates has discovered that evidence that could help solve burglaries in the county has been collected from crime scenes but never tested because the county crime lab put a hold on touch DNA testing of property crimes last year.
“Right now, we’re focusing our efforts on the most important crimes: the sex assaults. the homicides.
We’ll get back to property crimes soon and the opportunity arises,” Roger Kahn, the crime laboratory director of the Harris County Institute of Forensic Sciences, said.
The county doesn’t have the manpower to stay caught up on touch DNA testing of property crimes.
There are 2,743 touch DNA samples from property crimes, mostly burglaries, sitting untested at the Harris County Institute of Forensic Sciences’ Forensic Genetics Laboratory.
Kahn said the lab has not permanently stopped testing touch DNA, but has paused it so it can keep up with demand from major crimes.
Touch DNA is what is left behind whenever a human touches a surface. Only trace amounts are needed to test and make a match in a nationwide DNA database.
Touch DNA can be better than fingerprints because a fingerprint requires a print to be left behind, which requires a much larger surface than what is needed to process touch DNA.
The crime lab is processing some DNA from burglaries when certain samples come in, such as blood or a discarded cigarette believed to belong to the burglar. In these situations, Kahn says, there is a much higher probability that a match can be easily made.
A match with touch DNA can take days of testing because the DNA must be gathered from a piece of clothing that is much bigger than a drop of blood.
A single DNA test costs a minimum of $250, Kahn said.
He says it isn’t possible to test every sample that comes in from detectives in a property crime case. Sometimes investigators submit a dozen or more samples from one crime.
It is possible in the future, he says, that the crime lab will limit the number of touch DNA samples the lab will test from a single property crime.
That would allow the crime lab to test fewer samples from more individual crimes.
He does not believe the lab will limit sample numbers from sex assaults or capital murder cases.
“The sex assaults and homicides have to be job one, and any other crime against a person, including assaults and robbery,” he said.
Last year, the crime lab tested 2,750 samples. Individuals who had been convicted of crimes in the past were linked with the samples 550 times, Kahn said.
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