Doctor Charged in Matthew Perry Case Agrees to Plead Guilty

One of the doctors charged in connection with Matthew Perry's ketamine death is one step closer to doing hard time ... because he just copped to a slew of crimes.

According to new legal docs, obtained by TMZ, Dr. Salvador Plasencia -- one of 2 physicians busted in the Perry case -- has agreed to plead guilty to four counts of distribution of ketamine.

Federal prosecutors say they expect Dr. Plasencia to formally enter his plea in the coming weeks ... he's facing up to 40 years in federal prison, but both sides have agreed to recommend a sentence of 15 to 21 months, though it's ultimately up to the judge.

As we reported ... Plasencia was accused of supplying Matthew's assistant, Kenneth Iwamasa, with several vials of ketamine and showing him how to administer the drug. He was also accused of administering ketamine to Matthew.

Plasencia is the guy the feds say sent this message about Matthew ... "I wonder how much this moron will pay [for the ketamine]."

The other physician charged in the case, Dr. Mark Chavez, already cut a plea deal ... as did Iwamasa and Erik Fleming, who prosecutors say helped broker the drug deals.