The death of a 21-year-old Navy SEAL trainee in Califoia was ruled a homicide by drowning, San Diego medical examiners revealed Wednesday in a development that could lead to charges against at least one training supervisor.

Seaman James "Derek" Lovelace died in May after he was taking part in a swimming drill in Coronado. Surveillance video showed that as Lovelace was struggling to tread water in combat fatigues and boots, one instructor dunked the trainee's head under the water at least twice and splashed him, investigators said. Witnesses said Lovelace's face tued purple and his lips were blue.

After his head went underwater several times, the instructor finally pulled him out. The trainee lost consciousness soon afterwards, and paramedics rushed him to a hospital where he was pronounced dead, Naval Special Warfare Center spokesman Lt. Trevor Davids said.

"Although the maer of death could be considered by some as an accident... it is our opinion that the actions, and inactions, of the instructors and other individuals involved were excessive and directly contributed to the death, and the maer of death is best classified as homicide," Deputy Medical Examiner Abubakr Marzouk and Forensic Pathology Fellow Kimi Verilhac wrote in a statement.

"It is important to understand that 'homicide' refers to 'death at the hands of another' and a homicide is not inherently a crime," Naval Criminal Investigative Service spokesman Ed Buice responded. He said the Navy was still investigating and had not determined whether charges would be filed.

Medical records showed doctors previously had treated Lovelace for asthma.

The seaman was in his first week of training as a SEAL trainee after joining the Navy about six months earlier, Davids added.

Lovelace was bo in bo in Landstuhl, Germany, and dreamed of becoming a SEAL, according to a death aouncement from Whitehurst Powell Funeral Home and Southe Heritage Crematory in his home town of Crestview, Florida.

He enjoyed any activity on the water and played baseball at Crestview High School and Faulkner State Community College in Bay Minette, Alabama, according to the death aouncement. Lovelace joined the Navy and graduated basic training on Jan. 28, 2016, in Great Lakes, Illinois.

His death came days after another Coronado-based SEAL — Navy Petty Officer 1st Class Charles Keating IV — was shot and killed during a gunbattle involving Islamic State fighters in Iraq.

The Associated Press contributed to this report.