Conrad Murray's girlfriend testifies about alleged propofol shipments in Michael Jackson case

(CBS/AP) LOS ANGELES - The girlfriend of the doctor charged in Michael Jackson's death testified Tuesday about shipments, allegedly of the anesthetic propofol, that Dr. Conrad Murray had sent to her apartment.

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Prosecutors asked Nicole Alvarez, 29, about shipments that Murray had sent to her Santa Monica, Calif. apartment. She admitted receiving the items, but never opening them. Authorities contend the shipments contained propofol, which Murray was giving to Jackson as a sleep aid.

Authorities accuse the Houston-based cardiologist of giving Jackson a lethal dose of propofol and other sedatives in the bedroom of the singer's rented mansion. Murray's attorneys claim Jackson took the fatal dose himself.

In opening statements, a prosecutor said Murray had received more than four gallons of propofol while working for Jackson.

Alvarez, who has a child with Murray, also told jurors Tuesday that the doctor had first told her that he was Jackson's personal physician for a year before the singer's June 2009 death.

Alvarez beamed as she described meeting Jackson for the first time in Las Vegas, where Murray maintains a medical practice.

"I was speechless," Alvarez said. "I couldn't believe I was meeting Michael Jackson."

Alvarez said she and Murray met Jackson several other times, including after the birth of the couple's young son.

Alvarez says Murray would frequently leave her apartment at night and return early the next day. She says she knew Murray was working as Jackson's personal doctor as the singer prepared for a series of comeback concerts.

Phone records displayed in court Monday showed Murray called Alvarez four times the afternoon of Jackson's death, including once while he was in the ambulance with Jackson's lifeless body on the way to the hospital. 

Murray's former girlfriend Sade Anding testified earlier Tuesday, saying that her call with Jackson's doctor was interrupted on the day of the pop star's death. She said she heard voices, coughing and mumbling on Murray's end of the line. She told jurors that it sounded like his cell phone was in his pocket and that he had stopped paying attention to her.

Prosecutors are attempting to show that Dr. Conrad Murray was trying to juggle his medical practice, personal life and superstar patient all at the same time.

Murray has pleaded not guilty to involuntary manslaughter in Jackson's death. If convicted, he faces up to four years behind bars and the loss of his medical license.

Complete coverage of the Michael Jackson - Dr. Conrad Murray case on CBS News