Dr. Conrad Murray -- RELEASED FROM JAIL

Dr. Conrad Murray is a FREE MAN ... after serving a 2-year jail sentence for killing Michael Jackson ... and Murray didn't spend an extra minute in jail.

According to the L.A. County Sheriff's Dept. ... Murray was released at 12:01 AM Monday -- however, he did not make a triumphant walk out of jail ... choosing, instead, to sneak out away from photogs who had gathered.

By remaining unseen ... Murray obviously knows he raises the price tag of that coveted first interview with him.

A group of hecklers was clearly irritated they were not permitted to voice their disdain face-to-face -- and took it out on Murray's lawyer, Valerie Wass. As for why the L.A. County Sheriff's Dept. made the accommodation to keep Murray's release secret ... all they would say is "safety" and "security."

The good doc has been locked up since November '11 after being convicted of manslaughter. He was sentenced to 4 years in prison ... but 2 is normal for a 4-year sentence.

As we previously reported ... Murray plans to try and get his medical license back in Nevada and block revocation in California -- our sources say he doesn't stand a chance.

He's also looking to hire a publicist once he's out -- to help change his image.