Three young transients used a handgun that was stolen from an unlocked car to rob and kill a backpacking Canadian tourist in Golden Gate Park in San Francisco then a yoga instructor two days later on a hiking trail north of the city, authorities said Friday.

The handgun was reported stolen on Oct. 1 from the Fisherman's Wharf neighborhood in San Francisco, police commander Toney Chaplin said.

"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 Oct. 3 in Golden Gate Park. She had been shot in the head.

Yoga instructor Steve Carter, 67, was discovered dead on Monday near a popular hiking trail in Marin County across the Golden Gate Bridge. He had been shot multiple times while walking his dog.

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 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.

San Francisco police also said the suspects were in possession of Carter's car and some of Carey's camping gear was found inside it.

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, said Marin County sheriff's Lt. Doug Pittman. He declined to say how they will be transported but said they will not return this weekend.

"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. He was sentenced to time served in the weapons case and never showed up in court for the graffiti charge, the records state.

In 2012, he pleaded no contest to carrying a concealed 5-inch knife in Mountain View, California, the San Francisco Chronicle reported.

In May, he was charged in San Diego County with the unlawful selling or receiving of a stolen vehicle, a felony, and with stealing a dog, a misdemeanor, the newspaper said. He pleaded guilty to the felony charge and was sentenced to time that he had already served.

San Francisco detectives spotted similarities in the shooting deaths of Carey and Carter, including the locations in wooded areas. The agency collaborated with Marin County, which traced the three suspects to Portland using the navigation system in Carter's car.

Investigators are trying to piece together how the trio and the homicide victims met up. They're also trying to determine how long the suspects had been in San Francisco and how they got to Marin County.

Carey had left her native Quebec and was on a solo backpacking trip when she was killed after the first day of a music festival in Golden Gate Park. Her body was found near the site where the Hardly Strictly Bluegrass festival is held each year on six stages spread throughout the park.

Tens of thousands of fans stream into the park each year to watch the free music performed by dozens of bands over three days.

San Francisco police spokesman Albie Esparza said it's unclear if the suspects or Carey attended the festival because there are no tickets to the free event. Investigators believe Carey may have camped in the park.

A hiker found Carter's body Monday evening and he was still holding the leash of his wounded dog. The Doberman pinscher was turned over to the Marin County Humane Society and is expected to recover.

Followers credited Carter with improving their romantic relationships by teaching tantra, a philosophy of meditation, yoga and sexuality famously embraced by rock star Sting.

In July, police said a stolen gun was used by a Mexican national in the U.S. illegally to kill Kate Steinle as she walked along San Francisco's waterfront. The gun was previously reported stolen from the car of a Bureau of Land Management agent in downtown San Francisco.

Juan Francisco Lopez-Sanchez has pleaded not guilty to murder in the case.