Boyd, who was an opera singer and who'd released the album American Dream in 2009 after his AGT win, had reportedly been seeing multiple doctors for his health. He had heart failure, kidney failure and liver problems, the coroner said.
Last year, he and his mother were reportedly badly injured in a auto accident after he blacked out while driving.
The Missouri native opened up about the crash and his plans for new music in February. "It was a very, very, very bad wreck ..."
When news broke of Boyd's passing, British media personality Piers Morgan - who at the time was a judge on the Boyd's season, along with Sharon Osbourne and David Hasselhoff - expressed his sympathy on Twitter, as did celebrity gossip columnist Perez Hilton. "It's been hard, because you can't get up on stage right now, you can't perform for the audiences and you can't really do too much recording or traveling". He called the album "uplifting".
The Missouri native noted that "it just feels like something great is about to happen once I get back on my feet and back in front of the audience again".
Boyd briefly dabbled in politics, too: He ran for a seat in the Missouri House of Representatives twice, but was defeated both times. Just be grateful that you survived.
"You know, that's up in the air".
"I want to thank everyone who has taken part in helping Neal and I recover especially the first responders st francis medical center all the doctors and staff both in cape and st louis the air evac team and every one who has sent messages and posts [sic]", Esther wrote on her Facebook shortly after the auto accident.