BETHLEHEM, Pa. -

A bizarre beating case that stunned a neighborhood in Bethlehem is now a homicide case.

Shirley Lindgren, 77, died of her injuries at a hospital late Wednesday morning, said the coroner, who ruled her death a homicide. The coroner said her death was caused by severe head injuries.

Lindgren's son, Michael Lindgren, severely beat her and her husband Ralph, Michael's father, early Tuesday morning inside the couple's home on E. Wall Street, police said.

People who know the Lindgrens said Michael has a history of mental illness and sometimes doesn't take his medication.

Michael Lindgren was laughing and mumbling incoherently during a court appearance Tuesday afternoon. He allegedly told police he had to kill his parents.

Police said they expect to file additional charges against Michael Lindgren later this week.