BANGOR, Maine — The trial of a Bangor man accused of assaulting a woman with a field hockey stick Jan. 9 began Tuesday at the Penobscot Judicial Center.

Christopher Stone, 30, has claimed he struck the then 21-year-old woman in self-defense after she first hit him in the face with brass knuckles in the doorway to an apartment at Acadia Place in Bangor.

He has pleaded not guilty to Class B aggravated assault, Class C domestic violence assault and Class D violation of a protection order.

The argument was over a cellphone the woman had given Stone and wanted back, according to Michael Roberts, assistant district attorney for Penobscot County. The victim came to get the cellphone back at the apartment where Stone was staying with his then 18-month-old child and Teann Windsor, 30, the girl’s mother, the prosecutor said.

Windsor testified that the field hockey stick was hers and that she had played in seventh grade in 1996 or 1997 in northern Penobscot County.

“Stone went out of the apartment to talk with the victim,” Roberts said after court adjourned Tuesday. “He, then, pushed his way back into the apartment past [Windsor], who was trying to keep him out. When the victim confronted him, again at the door, he struck her with the field hockey stick.”

The victim fell to the ground but did not lose consciousness and has recovered from her injuries, Roberts said.

Defense attorney N. Laurence Willey of Bangor told the jury in his opening statement that the victim showed up with two men, who acted as “bodyguards.” Stone did not strike her with the field hockey stick until after she struck him more than once in the face with brass knuckles, he said.

The victim and Windsor both were romantically involved with Stone, Willey said.

Windsor, who admitted that Stone was staying with her despite the fact that a protection order was in place keeping them from having contact, told the jury that she did not see the victim strike Stone. She also said that she saw him grab the stick but did not see him hit the victim but could “hear the blows.”

“Stone called 911 and told the dispatcher that he was attacked by two men and a woman at a home on Acadia Place and that the three had knives and brass knuckles,” Lt. Paul Edwards of the Bangor police said in January.

Investigators determined he “was the aggressor, and had assaulted a female about the upper torso and head with the field hockey stick,” Edwards said.

Stone has been held at the Penobscot County Jail unable to make bail since his arrest Jan. 9.

The victim, who is not being identified by the Bangor Daily News, will take the stand Wednesday, Roberts said.

The jury of 11 women and three men, including two alternates, are expected to begin deliberating Thursday afternoon.

If convicted, Stone faces up to 10 years in prison and a fine of up to $20,000 on the aggravated assault charge alone.