JOE preparing wrongful death suit against DR. CONRAD MURRAY........HE GONNA BEAT HIM FOR SURE!!!

TMZ has obtained a copy of a legal document that Joe Jackson has sent to Dr. Conrad Murray -- a prerequisite to filing a wrongful death lawsuit ... in which Joe claims Dr. Murray had been drinking at a strip club hours before he allegedly administered a fatal dose of Propofol to Michael Jackson.

According to the document, "On June 25, 2009, prior to treating Michael Jackson, defendant was at a 'strip club' called 'Sam's Hofbrau' in Los Angeles where he had been 'drinking.'" The doc goes on: "It was reckless for him to 'drink' prior to administering anesthesia to Michael Jackson. He concealed his conduct from Michael Jackson."

The doc, written by attorney Brian Oxman, outlines Murray's treatment and the medical emergency that ended in Michael Jackson's death.

According to the document, Michael had "neurological, pulmonary, and anemia signs over several weeks prior to his death. In May and June, 2009, Michael Jackson was confused, easily frightened, unable to remember, obsessive, and disoriented." Oxman goes on: "He had impaired memory, loss of appetite, and absence of energy. He was cold and shivering during the summer rehearsals for his show ..."

Oxman claims these problems were caused by Dr. Murray administering a "polypharmacy" of drugs (multiple meds) to Michael. And Oxman claims, Dr. Murray "ignored the signs of Michael Jackson's pulmonary inflammation, brain swelling, and anemia."

Oxman alleges Murray repeatedly lied about the drugs he administered to Jackson and withheld vital information from EMTs and doctors who were trying to save Jackson's life. He repeated all of the alleged inconsistencies that have been previously reported.

Oxman says of Dr. Murray, "His conduct was inhuman. It was an extreme violation of the standard of care."

We're told Dr. Murray received a copy of the document in March. Dr. Murray's legal team tells TMZ, "The allegations are absolute, utter nonsense."

And people close to Dr. Murray insist he does not drink ... ever.

We're told the document was served on Dr. Murray on March 27, 2010. According to California law, Joe Jackson must wait 90 days from the date the document is delivered before filing an actual wrongful death lawsuit. The 90-day period is up Friday, the anniversary of Michael's death.