AceShowbiz - Michael Jackson's parents were fuming after Dr. Conrad Murray pleaded not guilty to an involuntary manslaughter charge on Monday, February 8 - insisting their son's former doctor should have accepted responsibility for "killing" the singer.

Dr. Conrad Murray walked free from court in Los Angeles after posting $75,000 bail, prompting the singer's elderly parents, Katherine and Joe, to speak out against the physician. Katherine ranted to reporters, "He's a monster... He should have pleaded guilty. He killed my son."

Meanwhile Joe told E! Online, "I didn't like today's hearing at all. I just want justice done and that was not justice."

Murray, who has denied any wrongdoing, surrendered to face allegations of administering a lethal dose of the hospital anaesthetic Propofol to the late singer - but he did not come face-to-face with any member of the Jackson clan.

The "Thriller" legend's sister La Toya Jackson, who was also present at the hearing, has vowed to "fight" until those responsible for the singer's death are brought to justice. She says, "Michael was murdered and although he died at the hands of Dr. Conrad Murray, I believe Dr. Murray was a part of a much larger plan. There are other individuals involved and I will not rest and I will continue to fight until all of the proper individuals are brought forth and justice is served."