SAN DIEGO (AP) — His lips turning blue and his face purple, the Navy SEAL trainee dressed in full gear was struggling to tread water in a giant pool when his instructor pushed him underwater at least twice — actions a medical examiner ruled Wednesday made his death a homicide, not an accident.

The homicide ruling on the May 6 drowning of 21-year-old Seaman James Derek Lovelace raises questions about the safety of the grueling training that produces the U.S. military’s most elite warfighters. It also raises questions about where the line is drawn between what is considered to be rigorous training designed to weed out the weakest and what is abuse that leads to a homicide.