Britney Spears’ first husband is in the slammer. On Wednesday, Jason Alexander began a 10-day sentence in Los Angeles County jail for a 2006 DUI arrest. The former Mr. Spears ended up behind bars because he failed to complete a court ordered alcohol rehabilitation program. “Jason messed up and he knows it,” an insider tells Star. “He’s going to keep his head down, stay out of trouble and hopefully he won’t have to serve the entire 10 days.” Britney married Jason, her childhood friend, at 5:30am on January 3, 2004 at the Little White Wedding Chapel in Las Vegas. The marriage lasted 55 hours ending in an annulment granted by the judge on January 5, 2004. These days Jason, 27, is living in LA’s San Fernando Valley working for a clothing company.

Says TMZ: Jason Alexander didn’t see dead people — so he saw a jail cell instead. TMZ has learned the real reason Brit’s 55 hour first hubby is behind bars in L.A. is because he blew off two court ordered appointments at the county morgue. After Alexander was busted for DUI back in 2006, the judge ordered the 27-year-old to go to an alcohol education program, which required him to visit the local morgue. When the judge learned Alexander had ditched his first 2 appointments, he refused to give him a third chance and promptly chucked him in the slammer. Jason is scheduled to be released on December 9th — and after he serves his stint behind bars, Jason’s obligation to check out the dead bodies will officially be dead.

LOL. This guy really sounds like a winner. And to think … he could’ve been the first Kevin Federline if Britney’s crack team of lawyers hadn’t swooped in and annulled his marriage to her and then sweeped him under the rug, never to be heard from again. He was SOO close. Ah well. Here’s hoping the lad learns his lesson that drunk driving doesn’t pay.

UPDATE: TMZ comes thru with the mugshot:

HMMM … looks like someone’s been hittin’ the gym. I’m sure this guy’ll be a big hit in jail.

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