A good sample of DNA can leave a genetic fingerprint at a crime scene. DNA samples can come from blood, hair, saliva or semen.
When DNA evidence is collected, the key is keeping it from deteriorating, said criminalist Christine Ogilvie of the Oregon State Crime Lab in Pendleton.
Genetic material properly transported and stored can be viable for thousands of years, she noted.
"It really has changed the face of forensics," Ogilvie said.
The procedure for matching a DNA sample with the data bank takes about three weeks, said Brian Ostrom, DNA unit supervisor for the State Police Crime Lab in Portland.
DNA samples are usually taken in major crimes, such as homicides or sex offenses. In Oregon, all felony suspects are required to give a sample of their DNA to be added to a computer database that can cross-reference genetic samples. But it's becoming more common to use DNA in burglaries and other nonviolent crimes as well.
"As resources become available we will start working some of the lesser crimes," Ostrom said.
Umatilla County District Attorney Chris Brauer said DNA has been instrumental is several cases over the years. "We've cracked cold cases in the past based on DNA," he said.