The son of former NFL quarterback Erik Kramer died of a heroin overdose, the coroner has ruled.

The Los Angeles coroners office said 18-year-old Griffen Kramer, a backup quarterback at Thousand Oaks High school, died of acine heroin toxicity, according to toxicological reports. Griffen Kramer was found dead on Oct. 30 in his Agoura Hills home.

Friends had said that Griffen Kramer was foaming at the mouth when using heroin with them. Law enforcement officials said one friend took him home as a result and put him to bed, hoping he would sleep it off.

The next morning, however, Griffen Kramer was found dead -- suspected of a drug overdose. It wasn't until the coroner's ruling this week, however, that the heroin overdose was confirmed. Kramer friend who had taken him home to sleep it off was arrested on a charge of suspicion of involuntary manslaughter, as was another friend reportedly using drugs with Kramer that night. In all, five were arrested in various charges from involuntary manslaughter to possession of heroin related to the teenager's death.

Griffen Kramer had dealt with drug issues before. Previously, he had attended part of his sophomore year of high school in a rehab center. He had hoped football would help him get away from drugs.

Erik Kramer, the teenager's father, was an NFL quarterback from 1987 to 1999. Kramer played with Atlanta, Chicago, San Diego and Detroit.