The death of 18-year-old James Dungy, the son of Indianapolis Colts coach Tony Dungy, has been ruled a suicide, a medical examiner said Friday.

In her autopsy report, Dr. Jacqueline Lee of the Hillsborough County Medical Examiner's Office wrote that James Dungy hanged himself from a bedroom ceiling fan with a leather belt.

In December authorities ruled out foul play. Toxicology results have now turned up negative, except for caffeine and medication paramedics used in attempts to resuscitate the teen, Lee said.

Dungy's girlfriend found him on Dec. 22 less than a half hour after he was last seen alive, according to the medical examiner's office. She called paramedics, who attempted to resuscitate the teen to no avail. He was pronounced dead at a Tampa hospital.

James Dungy had been taking extension classes at the University of South Florida, authorities said.

with files from Associated Press