Anthony Clark, 48, of Allentown, was immediately fired from his position after the incident on Feb. 2 at South Mountain Memory Care on Seventh Street in Emmaus, according to District Attorney Jim Martin and Emmaus Police Chief Jason Apgar.
Another worker entered the victim's room and witnessed Clark assaulting the woman, who had dementia and couldn't communicate, authorities said.
The investigation turned up evidence that was eventually matched to Clark's DNA, police said.
Clark was charged Thursday, July 28 with rape and involuntary deviate sexual intercourse, institutional sexual assault, and sexual assault.
Prosecutors said the victim passed away on June 15, but there is no evidence her death was connected to the rape.
"The administration at South Mountain Memory Care cooperated fully and completely in the investigation," Martin and Apgar said.
Clark was remanded to Lehigh County Jail in lieu of $500,000 bail, records show. His preliminary hearing is set for Aug. 5.
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