Michael Jackson's doctor

LOS ANGELES, Feb. 9 (UPI) -- The doctor who treated Michael Jackson prior to the pop singer's death has been charged with involuntary manslaughter.

Prosecutors in Los Angeles filed the charge Monday against Dr. Conrad Murray. Shortly afterward, Murray pleaded innocent to the allegations and is to return to court in April. He could be sentenced to four years in prison if convicted.

Members of the Jackson family said they had wanted the doctor to face a more serious charge, such as murder which could carry a life-in-prison sentence.

Jackson, 50, died June 25 of what LA coroners said was "acute propofol intoxication." The singer was being administered propofol, a powerful anesthetic, to help with a sleep problem.

Murray said Jackson had used propofol for years because of insomnia but the coroners' report cited an expert who said she knew of no reports that the substance had been used for that purpose.