ATLANTA (AP) — Atlanta police say they’ve arrested a fourth suspect in the slaying of an Atlanta restaurant owner last month.

Authorities say 53-year-old Vanessa Thrasher was preparing to testify in an upcoming murder trial when she was gunned down at her northwest Atlanta business, OT’s Lounge and Soul Food Grill, on Aug. 16.

Atlanta police Officer John Chafee said Tuesday night that 23-year-old Christopher Penson was charged with felony murder in connection with the killing. Fulton County Jail records did not indicate whether Penson has an attorney.

Chafee said Penson is the fourth suspect charged in the case.

Fulton County District Attorney Paul Howard has said that Thrasher was a key witness in the trial of a man charged with killing one of her employees in May 2011.