LOS ANGELES, Calif. (KTLA) -- The involuntary manslaughter trial against Michael Jackson's doctor, Conrad Murray, was entering its "CSI" phase Wednesday with police and coroner's investigators expected to take the stand.

Medical supply sales representative Sally Hirschberg testified Wednesday that Murray "raised a red flag" by requesting an infusion IV set to be shipped to a California residence. She instead mailed the supplies to one of Murray's clinics, according to Hirschberg's testimony.

Stephen Marx, the computer analyst who examined Dr. Conrad Murray's iPhone, also took the stand.

Marx testified that he retrieved several emails sent by Murray's assistant regarding "Omar Arnold" -- an alias Jackson allegedly used to secure prescription drugs.

The testimony comes one day after prosecutors paraded three of Murray's girlfriends in front of jurors, including one who claims she was on the phone with the physician when Michael Jackson stopped breathing.

Houston cocktail waitress Sade Anding testified that she was talking on the phone with Murray on the day Jackson died when the conversation was interrupted about five or six minutes in. She says she realized Murray wasn't listening to her.

Anding testified that when she pressed her cell phone against her ear, "I heard the mumbling of voices ... and I heard coughing, and nobody answered." Anding hung up the phone about three minutes later, she said.

Prosecutors allege that was the moment Murray realized Jackson was not breathing. Nicole Alvarez, the mother of Murray's 7th child, also took the stand. Alvarez, who lives in Santa Monica, testified that she received Murray's packages at the apartment they shared, but she didn't know the contents. Prosecutors allege the shipments contained propofol.

Murray reportedly met Alvarez, 29, at a Las Vegas nightclub.

On Monday, phone company officials testified Murray was busy on his cell phone between 10:45 a.m., when he is believed to have administered propofol to Jackson, and 11:56 a.m., when prosecutors say he interrupted a phone call after discovering Jackson had stopped breathing.

Former girlfriend Bridget Morgan testified Monday that she tried to call Murray on the day Jackson died but she didn't speak to him because "he didn't answer his telephone."

Doctors who tried to revive Jackson at UCLA Medical Center also took the stand, saying Murray never told them he gave the singer the anesthetic propofol as a sleep aid.

Medical examiners have determined Jackson, 50, died on June 25, 2009 from an overdose of propofol and sedatives.

Emergency doctors at UCLA Medical Center in Los Angeles said that Jackson was already dead when he arrived there.

Nevertheless, lengthy attempts were made to revive him before he was pronounced dead at 2:26 p.m.

"My assessment when he arrived was that he was clinically dead," said emergency room doctor Richelle Cooper, who was on duty at the emergency room the night Jackson died.

Murray told doctors that he had given Jackson only the sedative lorazepam.

"Had Dr. Murray told you he had given 25 mg of propofol at 10:30, would it have altered your treatment of Michael Jackson?" asked defense attorney Michael Flanagan.

"No," answered Cooper.