Salt Lake County district attorney announced a break in a 1974 cold case that involved a 21-year-old woman from Palo Alto.
Investigators credit an old DNA sample for leading detectives to a Washington man.
On Wednesday, the D.A. charged Gerald Walter Hicker with first-degree murder for the death of Barbara Jean Rocky.
She was attending Bringham Young University when she was killed.
Hicker, 56, was arrested Wednesday in Tacoma, Wash.
He is being held without bail, according to authorities.
Hicker and Rocky had just started dating when Rocky was killed, NBC11 reported.
Rocky was last seen on March 11, 1974.
The next day, a utility worker found her body at a Salt Lake City area canyon.
The coroner said she had been shot six times by a large-caliber pistol.
The case remained cold until October, when a detective took a soil sample from the original canyon crime scene to a laboratory, NBC11 reported.
The lab found a skin or nail sample matching a DNA sample volunteered by Hicker, according to the affidavit.
Rocky's mother still lives in the Bay Area. She has agreed to speak with NBC11's Diane Dwyer tonight. You can hear her reaction to the apparent break in the case on the 11 p.m. news.