For two years, Nancy Gavarone has kept a secret from her mother, who has dementia: the rape and murder in 2008 of her mother's sister, Jane Morgan, at age 84.

"To have to hear that her sister died and how she died would have killed my mother," Gavarone said Tuesday in Delaware County Court. "And I couldn't afford to lose her, too."

On Tuesday, Billy Williams, the Upper Darby man charged with the rape and murder of Morgan, pleaded guilty and was sentenced to 30 to 60 years in state prison.

Williams, 63, admitted killing Morgan in her Long Lane apartment in September 2008. His DNA was found under her fingernails. He lived in the same building and worked in a small grocery on the ground floor, often delivering groceries to Morgan.

Dressed in red prison garb and shackles, Williams showed little emotion as Gavarone read a statement to the court.

"We will never understand why, or how, a person could conduct such horrible acts against another human being - especially one who is elderly and frail like Aunt Jane," said Gavarone, of Bethel. She said her aunt trusted Williams as a "good friend."

The woman with a fondness for cats was discovered dead when she failed to answer her door after arranging a ride to visit a friend in a nursing home.

Morgan's death was originally thought to be from natural causes until the medical examiner ruled her death a homicide as a result of "asphyxiation associated with blunt-force injuries."

Williams had "staged" the body to make the death look natural. Morgan was found in her nightgown with a pillow on her lap.

James Wright, Williams' attorney, told the court Tuesday that his client was "ferociously addicted to alcohol" and had been drinking on the night of the murder.

"His recollection of events is sketchy at best," said Wright.

The District Attorney's Office had sought the death penalty. But because of the defendant's age and health condition, prosecutors agreed to a plea of third-degree murder.

Family members were supportive of the plea, said Stephanie L. Wills, assistant district attorney.

Williams served time in prison for a 1980 rape.

Williams on Tuesday also pleaded no contest to theft in a separate case. Prosecutors said he stole about $2,000 from another neighbor.