Updated

The custody battle for a dog named Chase -- or Bear -- is getting ugly.

Police arrested an Oregon State University student who has refused to return a dog she found last year to its original owner. Meanwhile, the Multnomah County District Attorney's has opened an investigation into whether the original owner was abusive toward the pet.

Jordan Biggs, 20, was booked into a Corvallis jail on a theft charge Friday and later released.

Biggs has said she found the dog earlier this year in Portland and then took him with her to Corvallis after failing to find its owner. She named the dog Bear and had it trained as a service animal to assist her when she has an asthma attack.

When she returned to Portland for a visit in May, the original owner spotted the dog and asked for its return.

The man, 30-year-old Sam Hanson-Fleming, filed a police report after Biggs declined. He also obtained a ruling from a Multnomah County animal control official supporting his ownership rights.

Biggs, meanwhile, hired animal rights attorney Geordie Duckler, who has filed a civil suit asking a judge to grant custody to his client.

Duckler described Biggs as "upset" Saturday and said the dog would remain at a Corvallis shelter while the Multnomah County District Attorney's Office investigates allegations that Hanson-Fleming abused the Siberian husky mix named Chase while under his care. Hanson-Fleming said the allegations are untrue.

Duckler said a private investigation through his office -- based on recorded statements, eyewitness testimony, private documents and court records -- found Hanson-Fleming kicked, slapped, beat and urinated on Chase in order to show "who was in charge."

The lawyer also said Hanson-Fleming regularly kept the dog in a cage that was too small for lengthy periods of time and never had him seen by a veterinarian. Moreover, visitors to Hanson-Fleming's apartment referred to the living conditions as a "pigsty," and Hanson-Fleming regularly made the dog "inhale significant amounts of marijuana smoke in order to amuse himself and his friends, and to psychologically torment the dog," according to Duckler.

Hanson-Fleming told The Oregonian newspaper on Saturday that the allegations of animal abuse and neglect are false: "They're just trying to turn the tables on me."

Hanson-Fleming told the newspaper he bit the dog on the cheek when he was a puppy, but that was to discipline him -- using the same method canine mothers do.

"I've never hit Chase, I've never kicked him," Hanson-Fleming said. "The only thing I've done is swatted him with a rolled up newspaper" to discipline him for chewing on shoes, he said.

Multnomah County prosecutor Norm Frink wrote in an e-mail that the allegations "have at least a superficial credibility." Sgt. Pete Simpson, a Portland Police Bureau spokesman, confirmed authorities were investigating.

Corvallis police and shelter officials referred all question to the Benton County District Attorney's Office, which would not speak about the controversy until Monday.