Welch is charged with first degree murder for the 1982 murder of Rose Baugh in Kennewick. He was arrested last week and released within the day because of a medical condition.
A fugitive warrant hearing is now set for Wednesday. Deputy Prosecutor Sandra Dickerson said the extradition hearing will focus on confirming Jack Welch's identity. She said this is done by fingerprints, photographs and testimony.
Dickerson said if after the hearing Welch does not voluntarily go back to Benton County, then Washington can get a governor's warrant to send him back.
Welch was identified as the suspect through DNA evidence collected in 1982.
Lewiston Police Detective Brian Birdsell said they were contacted in the case to get a fresh sample.
"(They) contacted us asking for our assistance in obtaining another DNA sample for Mr. Welch as well as a set of, what they call major case prints, an entire handprint, so they could submit those to their lab for further testing," said Birdsell.
Birdsell said a saliva sample collected was not enough to accurately use so, using a warrant, investigators gathered more evidence.
"Basically what they needed was a fresh sample with a sufficient sample size so that they could monitor it with the modern DNA technology that they're using now," said Birdsell.
Birdsell said advances in DNA testing have helped investigators in a number of cold cases.
"DNA wasn't really starting to be used prevalently in investigations until the mid to late 80's," said Birdsell. "The later part of the 80's is when CODIS (Combined DNA Index System) was put into place where they tracked DNA and had a clearing house for unknown samples."
And while DNA testing is becoming more standard in investigations, Birdsell said one of the best crime-solving clues is still the fingerprint.
"DNA is one of the top two," said Birdsell. "My favorite is still fingerprints. Because your fingerprint is your fingerprint. No one else has any other fingerprint like you, even if you're an identical twin."