Jurors in the trial of a Marion man accused of abusing his girlfriend's then 9-month-old son heard testimony Tuesday from medical personnel who treated the boy.

Prosecutors allege that 21-year-old Shane Phillip Nickerson beat the boy, now almost 2, and sexually assaulted him.

Doctors and nurses from Kalispell Regional Medical Center told the court that the boy was admitted with bruises, a bloody mouth, and injuries consistent with sexual abuse.

Acquaintances of Nickerson and his girlfriend also were called to the stand Tuesday, the second day of the weeklong trial.

Defense attorney Noel Larrivee is expected to argue that the boy's mother, an admitted drug abuser who even prosecutors concede is not a model parent, was responsible for his injuries.

The boy's mother testified Monday after a jury of six men and eight women, including alternates, was chosen earlier that morning.

Nickerson, who had been watching the boy, was arrested Aug. 9, 2008, after driving the injured child and the child's mother from his Wildebeest Lane cabin to the hospital.

The boy, later was flown to Sacred Heart Hospital in Spokane and spent three days in pediatric intensive care.

Nickerson pleaded not guilty in August 2008 to sexual intercourse without consent, sexual assault, aggravated assault, and one count of criminal endangerment, all felonies.

The Flathead County Attorney's Office added another charge earlier this month, accusing Nickerson of assault on a minor. He has pleaded not guilty to that allegation as well.

If convicted of all charges, Nickerson could be sentenced to more than 200 years in prison and fined $200,000.

Nickerson, who has been incarcerated since his arrest, also is facing unrelated assault charges for two separate alleged altercations with detention officers at the Flathead County jail.

He has pleaded not guilty to assault on a peace officer and attempted assault on a peace officer and is awaiting trial on those charges.