Conrad Murray Trial -- Key Witness Has VANISHED

Bizarre -- a pharmacist who testified he shipped MASSIVE amounts of Propofol to Dr. Conrad Murray in the weeks leading to Michael Jackson's death has disappeared without a trace, prosecutors claim.

According to prosecutors, Tim Lopez -- a former pharmacist at Applied Pharmacy Services in Las Vegas -- has mysteriously moved to Thailand and cannot be found.

Prosecutors now want a judge to let them use Lopez' previous testimony from the preliminary hearing in January -- when he claimed Dr. Murray ordered several large quantities of Propofol, beginning on April 6, 2009.