PHILADELPHIA (AP) – The father of a man accused of beating a third-year medical student to death with a baseball bat said his son suffers from bipolar disorder.

Farouk Ali told WCAU-TV on Thursday that his son had been hospitalized for the disorder, which causes moods to fluctuate between periods of depression and high-energy mania.

“It is not a secret that he has bipolar,” Ali told the Philadelphia station.

Nader Ali, 26, faces homicide charges in the beating death of Lea Sullivan, 25, who was attacked as she walked out of a grocery store onto a crowded downtown street Sunday afternoon. Police said the assailant clubbed her in the head and continued to beat her after she fell.

Witnesses took down the attacker’s license plate number, leading police to Ali, who was arrested Monday at his parents’ home.

Ali, a former medical student who was placed on leave from Jefferson Medical College last year because of what a spokesman called “an extreme change in behavior,” was a minor acquaintance of Sullivan’s.

Farouk Ali, who lives in Franklin Lakes, N.J., expressed condolences to the victim’s family.

“I feel very sorry for the victim’s family. I am very sensitive to what happened to her and I sympathize with her parents,” he said.

He called his son “very smart, very kind. What can I tell you? I’m shocked.”

Nader Ali has refused to sign a waiver allowing him to be returned quickly to Pennsylvania to face a murder charge. An extradition hearing was scheduled for early December.

AP-ES-11-12-04 0510EST