Hearing in Michael Jackson's Death Begins

(CBS/AP) It's been over a year since Michael Jackson died, but just today that a judge began hearing testimony to determine whether the superstar's doctor will stand trial for involuntary manslaughter.

Jackson had already died when Dr. Conrad Murray called for help, prosecutor David Walgren said in the Los Angeles courtroom.

Pictures: Michael Jackson: 1958-2009

Walgren argued that evidence would show that Murray also attempted to conceal that he had administered the powerful anesthetic propofol--perhaps a lethal does--to the pop superstar, ordering a bodyguard to collect items before paramedics were called.

Jackson died suddenly in June 2009 in the Holmby Hills home he was renting. Authorities contend Murray gave him a deadly amount of propofol and other sedatives in the bedroom of the mansion.

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"The evidence will show through the expert testimony, by all accounts, Michael Jackson was dead in the bedroom at 100 North Carrolwood prior to the paramedics arriving," Walgren said.

Murray had been giving Jackson propofol, an anesthetic normally administered in hospital settings, six nights a week for roughly two months before his death, the prosecutor said.

Murray's attorney, Ed Chernoff, declined to give an opening statement.

Jackson's mother, Katherine, and his sister LaToya and brother Jermaine attended the proceedings.

At the end of the multi-day hearing, a judge will determine whether there is enough evidence for Murray to stand trial. The Houston cardiologist has pleaded not guilty and his attorneys have said he did not give Jackson anything that should have killed him.