A Virginia man has pleaded guilty to killing an 80-year-old woman with a rock earlier this year — bludgeoning her to death in a stairwell after she questioned him about whether he lived in her building.

Online court records show Kurt Davis, 34, changed his original plea of not guilty for the Feb. 19 killing of Susan Williams, of Crystal Spring, to guilty on Monday after prosecutors showed evidence in court that they were planning to introduce at trial, including video of him talking to Williams inside her condo and attacking her, according to local CBS affiliate WDBJ.

Authorities were called to Williams’ apartment complex that Wednesday morning in the 2100 block of Yellow Mountain Road SE and found Davis standing over her near the southeast corner of the building — outside with a shovel — while Williams was lying there with “significant injuries,” the Roanoke Police Department reported.

“The preliminary investigation determined the victim was in a hallway of the apartment complex when she was assaulted,” RPD officials said. “It does not appear that the suspect and victim knew each other.”

Davis told cops he killed the octogenarian to “keep the peace” after encountering her in a hallway inside her complex, per WDBJ.

Surveillance video played in court by prosecutors showed Williams letting Davis inside her building, according to the Roanoke Times.

“Words can’t describe, I’m sure, what this community is feeling right now, what these neighbors, what this neighborhood is feeling right now,” RPD Chief Scott Booth told reporters in February. “The most important thing for us is to make sure that our case remains solid against this individual, and that he is held accountable for the heinous murder of Ms. Williams,” Booth said.

Court records show Davis had a jury trial scheduled to begin on Sept. 3 before he entered his guilty plea Monday. He has a lengthy criminal history — including arson, assault and burglary — and was said to have been homeless at the time of the killing, which landed him a first-degree murder charge.

“I have known Ms. Williams for 20 years,” Roanoke Mayor Joe Cobb told reporters after her death was first reported, according to WDBJ.

“She was a friend of mine; many of her family members are friends of mine,” Cobb said. “Like many in our community, I feel shock and anger right now.”

Williams has been described by friends and family as someone who worked with elderly residents in the area through the Local Office on Aging, with one colleague telling WDBJ that “that was her love … to take care of seniors.” She was reportedly the executive director of the LOA for more than 30 years and worked with the Council of Community Services.

“Never dreamed that something like that would happen to her, especially living in a safe building as she lived in that area of town,” said co-worker Shannon Abell. “I’m totally devastated and shocked.”

Davis is due back in court on Dec. 1 for a pre-sentence report.