The handgun was reported stolen on October 1 from the Fisherman's Wharf neighborhood in San Francisco, police commander Toney Chaplin said yesterday.
"We believe the same weapon was used in both crimes," Chaplin said, adding that it appears robbery was the motive in the two killings.
The body of Audrey Carey, 23, was found October 3 in Golden Gate Park. She had been shot in the head.
Authorities identified the suspects as Morrison Haze Lampley, 23; Sean Michael Angold, 24; and Lila Scott Alligood, 18. They were being held without bail in Oregon, and it was unclear if any of them are represented by a lawyer.
They were arrested on Wednesday at a soup kitchen in Portland, Oregon. San Francisco police say the stolen gun was recovered during the arrest, and they believe it's the weapon used to fatally shoot Carey and Carter.
Valerie Chapman, administrator of St Francis Church in Portland, said she had to admonish the three for smoking in a no-smoking area just outside the dining hall.
Some of the regular diners told her the three suspects were asking if anyone wanted to buy a Volkswagen Jetta station wagon, Chapman said.
"We serve low-income and homeless people, many of them with mental illness," Chapman said. "It's not the smartest place to sell a car."
The suspects waived extradition proceedings in Portland and will be returned to the San Francisco Bay Area to face charges in the shooting deaths, Marin County sheriff's Lt. Doug Pittman said.
"They can't go anywhere until we come get them," he said.
He has described the suspects as drifters and said none of them has a known address.
Records show Portland police arrested Lampley on suspicion of possessing a weapon in a park in 2010 and graffiti-related crimes in 2012.
