MILLVALE, Pa. — A 9-month-old boy found dead in a Pittsburgh-area apartment is believed to have starved after his mother died of an apparent overdose, leaving no one to care for him, authorities said Friday.

The woman's brother found the two dead early Friday morning when he went to check on his sister, Sara Kessler, 22, after not hearing from her for several days, Assistant Allegheny County police Superintendent James Morton said.

Morton said Kessler may have died a week or two earlier. She was found on her bed, with the son, Casey, in the living room. He said there were no signs of foul play.

"It's a very sad situation in there," Morton told reporters outside the apartment in Millvale, just across the Allegheny River from Pittsburgh. "It seems like he (the infant) tried to survive but there was no food or anything for him to have."

The woman's mother died of natural causes in the same apartment in November, Morton said, and no one else lived on the same floor of the apartment building.

Police suspect the woman died of a drug overdose.

Autopsies were scheduled for Saturday.