The shooting was linked to earlier cases because of similarities and forensic evidence, said Mesa police Sgt. Chuck Trapani.
Authorities say the so-called "Serial Shooter" is responsible for three dozen shootings of people, dogs and horses. The shootings have generally happened late at night, with no witnesses. Six people were killed and 17 — mostly pedestrians and bicyclists — have been wounded since May 2005.
Robin Blasnek, 22, was walking to her boyfriend's home in Mesa, a suburb east of Phoenix, at about 11:15 p.m. Sunday when she was gunned down. Neighbors heard a shot and ran to help the young woman, but she soon lost consciousness and died at a hospital.
Her father told the East Valley Tribune that Blasnek grew up as a special needs child and lived part time with her parents in Mesa and a group home in Tempe.
"She was just a great kid. Very, very naive, and pure as far as not understanding the dangers of the world," Steve Blasnek said. "I guess my only regret is that I didn't give her a big hug."
Trapani said Mesa police plan to beef up patrols and have assigned a detective to the Phoenix police serial criminal task force.
That unit already has about 200 officers working to try to solve the serial shooter case, plus another case involving a serial criminal dubbed the Baseline Killer.
The Baseline Killer is believed responsible for killing seven women and one man and sexually assaulting 11 women and girls during the past year. Police think his most recent killing was the shooting death of 37-year-old woman at a Phoenix car wash June 29.
A $100,000 reward is being offered for any information leading to the capture of either killer.