Three of Dr. Conrad Murray's girlfriends took the witness stand today in his involuntary manslaughter trial, describing their exchange of phone calls and text messages with him on the day Michael Jackson died.

Nicole Alvarez, the 29-year-old mother of one of Murray's seven children, said she spoke to him while he was in the ambulance with Jackson.

She was at times combative with the prosecutor and revealed to jurors that she and Murray currently live together. Murray could face four years in prison if convicted of involuntary manslaughter in the death of Jackson.

Alvarez said she and her newborn son at the time had planned to accompany Murray as he traveled with Jackson for the singer's 50-night comeback tour dubbed "This Is It." Jackson suffered an overdose from the powerful anesthetic propofol after a night of rehearsing for the tour June 25, 2009.

Prosecutors contend that Murray was reckless in administering the creamy anesthetic to Jackson and abandoned him by not properly monitoring him or by being forthcoming with first responders and emergency room doctors about the singer's drug use.

Alvarez told jurors that she received a call from Murray as he rode in an ambulance with a dead Jackson.

"I remember him telling me that he was on the way to the hospital in the ambulance with Mr. Jackson and for me not to be alarmed … because he knew I would learn this through the news," she said.

Alvarez told jurors that she received several packages for Murray beginning in April 2009. Prosecutors contend those packages contained propofol and other sedatives.

He said "that he was going to be receiving something, that if there was knock on the door, it was going to be a delivery that I could retrieve it for him," Alvarez said.

She claimed that she never opened the packages or asked about their contents.

Michael Jackson's Fingerprints Not on Propofol Bottles

ABC News has learned from sources close to the investigation that all propofol bottles found in Jackson's bedroom or on Murray did not have Jackson's fingerprints on them. That revelation may deal a blow to the defense's theory that Jackson himself took a powerful dose of propofol and the sedative lorazepam without Murray's knowledge, creating a "perfect storm in his body that killed him instantly."

Alvarez met Murray in 2005 at a Las Vegas club. In 2008, she testified that she learned that Murray was Jackson's doctor. She also met the singer.

"It actually was a surprise…he [Murray] said he wanted me to meet someone so I didn't know where I was going and that was what happened. I was speechless when I met him. I couldn't believe I was meeting Michael Jackson," she said.

In March 2009, she gave birth to a son and Jackson took an interest in the child, requesting visits to see Alvarez and the boy.

"Michael was very interested in the baby…he wanted to schedule visits so that he could see my son," Alvarez said.

Alvarez told jurors that between April and June 2009, Murray would leave at 9 p.m. for Jackson's home and return in the morning to her Santa Monica, Calif., apartment.

"In the beginning when he was working for Michael, he would come back really early…and then it became later and later," she said.

Alvarez, an actress, said that Murray paid her $2500 monthly rent. She said that even though he was paying her rent, she was still working as an actress.

Conrad Murray Exchanged Calls, Texts With Girlfriends on Day Michael Jackson Died

"As a professional actress, my daily duties consist of maintaining my instrument…Acting is a little bit different than a 9 to 5 job…as an actor, your instrument is yourself," she said. "I was working, I was auditioning and I believe I had at that time, I had several national commercials at that time on air."

Two more of Murray's girlfriends also testified. One was working at a Houston steakhouse when she met Murray in 2009. She received a call from the doctor at 11:51 a.m. on June 25, 2009, less than half an hour before a frantic Murray called Jackson's personal assistant and screamed for help at Jackson's chef.

"What he said to me was hello, it's Conrad Murray and he said, how are you doing. I said hello, how are you," said Sade Anding. "He just said well and then paused."

Anding said that she interrupted him and talked for an additional 3 to 4 minutes before realizing he wasn't listening.

"I realized he was no longer on the phone…I said hello, hello and I didn't hear anything, that's when I pressed the phone on my ear and I heard mumbling of voices…I heard coughing and nobody answered," she said.

When Los Angeles detectives reached out to Anding after Jackson died, she contacted Murray for help.

"He told me what, why, why are they calling you. I'm so sorry that they're contacting you and now you know, now you're in this. I'm going to give you my lawyer's number and make sure before you speak to LAPD, you have my lawyer present," Anding told jurors.

A third girlfriend Michelle Bella testified about meeting Murray at a Las Vegas club in February 2008 where she was working. Murray sent her a text message on the day Jackson died.

The contents of that message were not revealed.

Murray's one-time girlfriend Bridgette Morgan told jurors Monday that she called Murray on the day of Jackson's death, but that he didn't pick up the phone.

Source: ABC/MJackson.com