A stranger allegedly followed a grandmother in Georgia to her home and choked her to death, crushing her neck with his knees and full body weight while she lay on the ground, according to police and family members.

Hector David Sagastume Rivas, 21, faces charges for the murder of 52-year-old Camillia Williams, which police say occurred between 11 p.m. on March 12 and 1 a.m. on March 13. Cobb County police alleged that Sagastume Rivas strangled Williams and left her body in a yard near her Marietta home, discovered last Thursday morning.

“She didn’t know him,” the victim’s brother, Tony Williams, told Atlanta’s Channel 2 Action News.

Another brother, Arsene Williams, said Williams told family members that a stranger had been following her from a dollar store a night before the killing.

Police said the suspect did not disclose a motive for the alleged murder but admitted to killing Williams. He told investigators he used his knees after his initial chokehold attempt failed.

The investigation is ongoing. Anyone with information should contact the Cobb County Police Department’s Major Crimes Unit at 770-499-3945 or submit anonymous tips through Crime Stoppers at 404- 577-TIPS (8477).

“I’m glad that the investigation went so easy and so well and I want to thank the state of Georgia and Cobb County for bringing my sister to justice,” Arsene Williams said.

Family members called the killing “mind blowing,” adding that Williams was a beloved mother of five and a grandmother.

Check back for updates.

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[Feature Photo: YouTube via 11 Alive]