The case against Dr. Conrad Murray, the doctor accused of killing Michael Jackson, went to jury on Thursday.

During closing arguments on Thursday, prosecutor David Walgren argued to jurors that Murray was a liar and greedy opportunist who had no regard for Jackson’s wellbeing.

"Conrad Murray is criminally liable for the death of Michael Jackson," he told jurors, according to the Associated Press. "Not because it was Michael Jackson but because Conrad Murray is guilty of criminal negligence."

Walgren also rebuked the testimony of Dr. Paul White, a leading expert on the surgical anesthetic propofol, who testified in Murray’s defense and said that Jackson likely injected himself with the drug, causing his own death, the Los Angeles Times reports.

Testimony in the trial came to a close on Tuesday. In a shocking move, Murray chose not to take the stand in his own defense.

Murray, Jackson’s primary physician, had pleaded not guilty to involuntary manslaughter charges in the death of the singer. Prosecutors charge that Murray gave Jackson a dose of the anesthetic propofol in the bedroom of Jackson’s mansion that ultimately killed the singer on June 25, 2009.  Defense attorneys claim Jackson self-administered the dose when Murray left the room.

If convicted, Murray could receive a minimum sentence of probation or a maximum of four years, but he could serve jail less time due to jail overcrowding.

Superior Court Judge Michael Pastor told jurors to begin deliberations on Friday.