Officers responded nearly 1,000 times in the past three years to an Iowa juvenile treatment center where a staff member was killed by a 15-year-old resident, according to police records.

Kathleen Galloway-Menke was assaulted May 8 at the center, Ellipsis Iowa. Her family’s attorney, Trever Hook, said the 50-year-old mother of two daughters suffered brain damage and died Tuesday after life support was removed.

Galloway-Menke had worked at Ellipsis for a year. Hook questioned whether the facility provides adequate training for staff dealing with sometimes dangerous clients.

The 15-year-old had a violent history and had made previous threats against Galloway-Menke, Hook said. He wasn’t sure what prompted those threats.

The Polk County Attorney’s Office on Thursday announced that the 15-year-old has been charged with second-degree murder. He is being housed in a juvenile detention center. A news release did not say if the teenager would be tried as an adult. It wasn’t immediately clear if he had an attorney.