Conrad Murray -- FBI Investigates Death Threats

The FBI is investigating death threats made in connection with Conrad Murray's release from jail ... and it appears they're being made by a group of Michael Jackson fanatics.

Law enforcement sources tell us ... the threats have been targeted at Murray's lawyer, Valerie Wass. Here are some of them:

-- "One blow to the head is all you need."
-- "If you think MJ fans are insignificant ... you are dead wrong, DEAD wrong"
-- "Better get that hair brushed and be ready because MJ fans will be everywhere setting yours and Murray's lies straight."

As for why the fans are targeting Wass, there are 2 reasons. First, because they don't know how to reach Murray. The second reason is based on video from the night of Murray's release, when Wass confronted a screaming Jackson fan who claimed Murray was a murderer. Wass fired back, "If you were not so ignorant, you would know he was not convicted of murder!" And she continued to rant.

Wass also said after Murray's release, "There's a small group of these Jackson fanatics. They're annoying, but insignificant."

We're told Wass called the FBI and was told they would investigate.