Dr. Conrad Murray -- The Interview that Sunk Him

Dr. Conrad Murray would NOT be on trial today for Michael Jackson's death ... had he politely declined to speak with cops 2 days after MJ passed ... law enforcement sources tell TMZ.

Sources directly connected with the decision to prosecute Murray tell TMZ ... Murray's 2-hour interview with LAPD detectives at the Ritz Carlton Hotel in Marina del Rey gave prosecutors the ammo to charge the doc.

Our sources all say, prosecutors almost declined to file the case, but the police interview made all the difference.

We're told ... police and prosecutors believe they never would have been able to prove Dr. Murray administered Propofol to Jackson almost every day for 2 months, were it not for Murray volunteering the info. The case hinges on Murray's alleged reckless medical treatment, and prosecutors believe administering the drug in a home setting for that period of time proves recklessness.

And, our law enforcement sources say, cops could never have proven that Murray pumped a total of 5 gallons of Propofol through MJ's system were it not for the interview.

But there's something even more fundamental. We're told it became apparent to detectives shortly after Murray's interview that the doctor wasn't telling the whole truth. As one law enforcement source put it, "He told the truth 70% of the time during the interview, and lied 30% of the time. And the lies created the suspicion that led to the investigation that led to charges being filed."