LOS ANGELES (CBS) — Closing arguments began Thursday in the involuntary manslaughter trial of Michael Jackson’s doctor, Conrad Murray.

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Los Angeles County Deputy District Attorney David Walgren is trying to convince a jury of seven men and five women that Murray was responsible for Jackson’s death in June 2009.

Prosecutors have argued that Murray acted in a criminally negligent manner after giving the singer a powerful dose of the anesthetic propofol as a sleep aid.

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Lead defense attorney Ed Chernoff is likely to argue Jackson caused his own death by taking a deadly dose of propofol when Murray left his bedroom.

The jury has heard from 49 witnesses and listened to complex medical testimony during the first six weeks of the trial. They also heard several audio files, including a disturbing recording of Michael Jackson, as well as Murray’s police interview.

Closing arguments began with the judge’s instructions to the jury on how they should interpret evidence in the case.

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Murray faces up to four years behind bars and will lose his medical license if he’s convicted.