AUGUSTA – A police officer testified Tuesday that the Portland man charged in the beating death of his one-time girlfriend repeatedly apologized after his arrest.

The prosecution began calling witnesses in the trial of Gregory Erskine, 51, who is charged with murder in the fatal assault of Lisa Deprez, 42, with whom he had a three-year relationship.

Portland police Officer Jessica Goggins testified in Kennebec County Superior Court that while she was driving Erskine from the Portland police station to jail, he kept saying that “if she dies, he’d die.”

“He looked right at me and said, ‘I’m sorry,”‘ Goggins said. “He said, ‘It was just an argument that got out of control.”‘

The case highlighted the problems in the state’s system of protecting victims of domestic violence. Just days before Deprez’s death, Erskine was arrested for threatening to kill her and then released on $200 bail.

The judge who approved the bail did not know about violent episodes in their relationship, or other complaints of domestic violence against Erskine.

Assistant Attorney General Fernand LaRochelle told jurors Tuesday that Deprez and Erskine spent the afternoon of May 13, 2004, drinking in several Portland bars before going back to Deprez’s apartment on Cumberland Avenue.

Shortly after 8 p.m., Deprez’s downstairs neighbors heard a loud banging and what sounded like a woman’s voice calling for help.

They called police, who found Deprez lying on the floor, covered with a blanket and apparently not breathing.

She had blood on her hands, blood on her face and blood matted in her hair. She died two days later at Maine Medical Center; an autopsy showed swelling of the brain.

Police arrested Erskine after he ran down three flights of stairs and into the street. When he was apprehended, he was handcuffed and taken to police headquarters in a van.

The driver of the van, Officer Gail Petty, testified that she overheard Erskine say, “Thank you, thank you, thank you for stopping me.”

“He just kept repeating it over and over again,” Petty said.

Erskine’s attorney urged jurors to not jump to any conclusions until they have heard all the evidence.

“This case is all about preconceived notions and fulfilling expectations,” said Robert Ruffner, a Portland lawyer. “The police had preconceived notions and everything they did was based on … fulfilling those expectations.”

Erskine has been held at the Riverview Psychiatric Center in Augusta since he refused to eat at the Cumberland County Jail after his arrest. He has been evaluated at Riverview and found competent to stand trial.

Outside the courtroom, Deprez’s brother, Shaun Deprez of Limington, said his sister was trying to escape Erskine but could not.

He said that even though Erskine was ordered by a judge to stay away from her in the days before her death, she took him back “out of fear.”