ST. LOUIS (AP) – A St. Louis teenager is charged with first-degree murder in the strangulation death of Vashon High School’s co-valedictorian and homecoming queen.

Authorities say Leonard Johnson was the sometimes boyfriend of 18-year-old Sarah Billingsley-Walker. She was found dead Monday night at a home. An autopsy on Tuesday revealed she had been strangled.

Johnson was arrested and charged on Wednesday.

Relatives say they had warned Billingsley-Walker to stay away from Johnson, who they say had shown signs of violence.

Police responded to a home Monday night and found the body of 18-year-old Sarah Billingsley-Walker.

Authorities say there were no obvious signs of trauma.

Billingsley-Walker was also a National Honor Society member at Vashon High School and a member of the school dance team.