The Allegheny County Medical Examiner says autopsy results have confirmed than an 89-year-old dementia patient died of hypothermia when she wandered onto the roof of a Pittsburgh hospital in December.

The autopsy report calls the death of Rose Lee Diggs accidental.

The Pittsburgh woman's family is suing the University of Pittsburgh Medical Center. They claim the hospital network covered up a broken lock on a door to the roof at UPMC Montefiore, where the woman was found dead about Dec. 3 about 8 a.m. Diggs was last seen in her room about 5 p.m. the day before.

UPMC attorneys have said claims that hospital officials sought to cover up factors leading to Diggs death are "scandalous" and "preposterous." They have asked a judge to dismiss the lawsuit, but no ruling has been made.