More than a week after a man called 911 and claimed his girlfriend shot herself, he has been charged with her murder, according to Gwinnett County police.

Police accused 30-year-old Lawrence Gray of Gainesville of killing Katlyn Head, the department said in a statement Monday.

Head, 30, was a home healthcare worker and Gainesville resident, according to her obituary.

Investigators said Gray called 911 on July 22 and said Head had shot herself while sitting in their car on I-985 in Buford. Homicide detectives gathered evidence and spoke to witnesses at the scene, Gwinnett police said.

An autopsy by the Gwinnett County Medical Examiner’s Office determined the death was a homicide, police said. On Friday, officers obtained warrants accusing Gray of aggravated assault, aggravated battery and felony murder, officials said.

An investigation is ongoing.

“Investigators believe that there may be witnesses in this case who were on the interstate that day,” police said.

Anyone with information is asked to contact the police department at 770-513-5300. Tipsters can remain anonymous, and be eligible for rewards of up to $2,000, by contacting Crime Stoppers Atlanta at 404-577-8477, texting information to 274637 or visiting the Crime Stoppers website.