Orange County Sheriff's Department spokesman Jim Amormino told ABCNews.com today that officers were called to Levens' condo in an upscale Laguna Niguel neighborhood around 2:30 p.m. on Wednesday after McLean-Levens' mother found the couple dead in bed.
Both were found with a single gunshot wound to the head and while it's still an "active investigation," Amormino said, police believe Levens is the likely shooter.
Amormino said police were unsure how long the couple had been dead, but "it appeared at least a couple of days."
Autopsies were scheduled for today and police will also conduct ballistics and residue testing.
A Promising Start
Levens fought with several professional mixed martial arts organizations, including the high-profile Ultimate Fighting Championship, Palace Fighting Championship and the International Fight Leagues.
He burst onto the scene, winning his first seven fights in a row. But he had lost his last five, with his last fight coming in October 2007.
Tom Atencio, vice president of Affliction, a young California-based mixed martial arts organization, said Levens was one of his best friends.
The two met about five years ago while training together. Levens, he said, spoke of a hard life growing up in the Philadelphia projects and leaving home as a teenager. But Levens never offered much detail about his troubled childhood, and Atencio said he didn't push.
"He was a tough kid," he said. "He had a hard life."
And mixed martial arts, he said, "was the one thing he was good at."
Atencio said Levens was a well-liked, aggressive fighter.
"He fought mostly with instincts," he said. In those first seven wins, he pounded his competitors into submission, with none of the fights ever going past the first round.
Atencio said his friend had been let down by nearly everyone in his life and had trust issues. He married McLean-Levens earlier this year in Las Vegas.
Atencio said he couldn't even comprehend that his friend was being suspected in a possible murder-suicide.
"Whatever they find is whatever they find," he said. "Anybody that grew up the way Justin grew up, you can't fault."
Levens' History of Drug Use
Mixed martial arts is a rapidly growing fighting sport that puts two competitors in either a cage or a ring -- most professional organizations in the U.S. use a cage -- where they fight using a combination of judo, kickboxing and boxing, among other sports.
While it is not legal in all 50 states, including New York, most states have sanctioned and regulated the sport through local athletics commissions.
Chris Palmquist is a partner with Mixed Martial Arts LLC, which operates a community-based online forum where fans can post messages, read news and watch videos. Mixed Martial Arts LLC is also the sport's official record keeper.
Palmquist said he didn't know Levens personally, but that he was well regarded as a competitor even though he took the toughest fights possible, "almost to a fault," he said
"He would fight anybody," Palmquist said.
In July, Levens tested positive for the narcotic pain reliever oxymorphone, leading the California State Athletic Commission to suspend him Jan. 15. He was also fined $1,000.
Amormino said police confiscated prescription drugs from Levens' house. He couldn't say which specific medications were taken, but described them as "pain-killing, anti-depressant-type drugs."
Palmquist said that drugs, including steroids, come up in mixed martial arts "like any other sport."
Levens' Death Similar to Benoit
Levens' death is reminiscent of the 2007 murder-suicide of WWE wrestler Chris Benoit, his wife and their seven-year-old son. Police determined the wrestler killed his family and then himself.
It's a comparison that has not been lost of the legions of Internet posters that have commented on Levens' death.
Poster "slam12" wrote on the Web site Sherdog.com wrote, "R.I.P. its sad when stuff like this happens, with mma just getting into the mainstream eye in the past couple of years I hope it doesn't start getting the bad publicity pro wrestling gets all the time because of instances just like this. That is the last thing the sport needs."
Amormino said police had been called to the house twice recently -- once in November for a report of smoke coming from the house and once in October for a reported overdose. But Amormino said he has conflicting reports as to whether that call was for Levens or his wife.
Atencio said he doesn't want the world to remember his friend as a bad person.
"He was a good kid," he said. "He just had a lot of demons."