Sadly, the Summer of Celebrity Death is not over; Friday evening, celebrity DJ Adam Goldstein, known more commonly as DJ AM, was found dead in his Manhattan apartment. He was 36 years old.While the official cause of death has yet to be determined, rumors have been flying. Sources tell TMZ that DJ AM had been "completely devastated" over a recent breakup with his girlfriend, Hayley Wood (she was the one to call off the relationship). Sources close to Goldstein also revealed that he was having difficulty dealing with post-traumatic stress from the plane crash he survived in September 2008. The crash killed four people, and Goldstein and Blink-182 member Travis Barker were the only survivors. Many fans have begun speculating that, despite being sober for the past nine years, the breakup and stress over the crash may have caused Goldstein to begin using drugs again.

Addiction specialist Dr. Drew Pinsky said Saturday that pain medications prescribed after the plane crash may have led Goldstein away from his sober path. "It very slowly and subtly reawakens addiction," Pinksy said of pain medication in an interview Saturday. "I'm not saying it was inappropriately prescribed; I'm saying he didn't know the risks." A medical examiner's office spokeswoman said Saturday that toxicology tests, expected to take weeks, are needed to determine what killed Goldstein. An autopsy was inconclusive, said spokeswoman Ellen Borakove.

Whatever the official cause of death, Goldstein's friends, family and fans are in mourning. "I am absolutely heartbroken. For those of us lucky enough to have known him, Adam radiated a contagious exuberance for life and also personified the very definition of a true friend," said Mandy Moore, who dated Goldstein for two years.

Barker expressed his emotions in his own way. "Don't know how I am gonna play 2night but I am for AM," the drummer, 33, posted on Twitter Saturday night. "My brother is gone. I love u and miss u." He continued: "I'll never forget everything we've been through and every time I play the drums, I'll think of you. U were an amazing friend/DJ/human being."

The music world has lost another brilliant artist as the summer draws to a close. Hopefully, the fall will bring brighter times.