MIAMI, Fla.—A South Florida teen died of a lethal drug overdose in front of a live online webcam audience 12 hours after he started blogging about his plan to commit suicide, an investigator said Friday.

Abraham Biggs, 19, died Wednesday from a toxic combination of opiates and benzodiazepine, a drug used to treat insomnia and depression, said Wendy Crane, an investigator with the Broward County medical examiner's office. At least one of the drugs was prescribed to him and it's unclear how he got the others, Crane said.

Some of those watching encouraged Biggs, others tried to talk him out of it, and a few were debating whether the dose he took was lethal, Crane said. It's unclear how many people were watching.

Biggs stated his intentions on a forum at bodybuilding.com, where some users said they did not take him seriously because he had made previous statements about killing himself, Crane said. Biggs posted a link from there to Justin.tv, a site that allows users to broadcast live videos from their webcams.

Someone finally notified the moderator of the body building site's forum, who traced the teen's location to Pembroke Pines and called police, Crane said. Biggs was dead by the time they got to his house around 3:30 p.m. Wednesday, Crane said. He had started blogging at 3 a.m.

"He was just seen laying on the bed at that point," she said.