Michael Jackson's personal physician was formally charged with involuntary manslaughter in Los Angeles today for the singer's death. Dr. Conrad Murray appeared briefly at an arraignment hearing this afternoon, where he pleaded not guilty to the single felony charge. If convicted, he could face up to four years in prison. Murray's bail was set at $75,000. The judge also barred him from prescribing any anesthetics and suspended his passport. According to the criminal complaint, Murray is accused of killing Jackson "unlawfully, and without malice," by acting "without due caution and circumspection." Specifically, Murray administered the powerful sedative propofol to Jackson just hours before the "King of Pop" died from cardiac arrest at his Los Angeles home last June. Murray has extensive ties to Southern Nevada. Last summer, Murray's Las Vegas home and offices were raided as part of the investigation, and just last week he was a no-show at a Las Vegas court hearing in a lawsuit filed against him by a local company for unpaid bills. The judge in that case entered a default judgment against Murray. He's due back in court on the manslaughter charge April 5th.