The doctor charged over Michael Jackson’s death bought 255 vials of a powerful anaesthetic in the three months before the singer died from a lethal combination of the drug and other sedatives, a pharmacist has testified.

Conrad Murray purchased four shipments of the anaesthetic propofol between April 6 and June 10, 2009, said Tim Lopez, owner of Applied Pharmacy Services in Las Vegas, where Dr Murray has a clinic.

Dr Murray bought 130 vials of propofol in 100-millilitre doses and another 125 vials in the smaller dose of 20 millilitres, Mr Lopez said while testifying at a preliminary hearing to determine if there is enough evidence for Dr Murray to stand trial after pleading not guilty to involuntary manslaughter.

A coroner’s investigator previously testified that 12 vials of propofol were found in the bedroom and closet of the singer’s rented mansion after his death.

Mr Lopez said Dr Murray asked him to ship some of the propofol to an address in Santa Monica, California. The address belongs to the doctor’s girlfriend, although Mr Lopez testified that Dr Murray told him it was one of his clinics.

Dr Murray also bought other sedatives from Mr Lopez, according to the testimony.

Dr Murray has told police he was concerned Jackson was addicted to propofol, and that he was trying to wean the singer from it.

In other testimony today, a retired federal investigator said he had retrieved an email from Dr Murray’s mobile phone containing an exchange between the doctor and a London insurance broker handling a policy for Mr Jackson’s planned series of comeback concerts.

The broker asked Dr Murray on the morning of Jackson’s death to address press reports that Michael Jackson was in poor health.

“As far as the statements of his health published by the press, let me say they’re all malicious to the best of my knowledge,” Dr Murray replied.

Superior Court Judge Michael Pastor ruled before the hearing began today that the information could be introduced as evidence.

Dr Murray’s defence attorney, Ed Chernoff, had described some of the data as brief voicemails. He also said there were 12 screenshots found on the phone.

Judge Pastor said some of the information was protected by attorney-client privilege, but most is not.

Prosecutors have used Dr Murray’s phone records to help create a detailed timeline of the doctor’s actions on the day Michael Jackson died.

Prosecutors were poised to focus on the science of what killed Jackson during the second week of the hearing.

The hearing has included a significant amount of prosecution evidence. Among the witnesses was a bodyguard who said he was told by Dr Murray to place vials of medicine in bags before calling an ambulance.

Paramedics and an emergency room doctor with a combined 50 years of experience also said they believed the singer died before he was rushed by a paparazzi-hounded ambulance to a nearby hospital, where efforts failed to revive the pop superstar.

Using phone records and testimony from police and Dr Murray’s current and former girlfriends, prosecutors have developed the timeline that shows Murray was on the phone throughout the morning of Michael Jackson’s death on June 25 2009, including after administering propofol to the singer.

They hope to convince a judge of several key points: that Murray was distracted when he should have been monitoring Jackson, that he delayed calling an ambulance, that he botched CPR efforts and that the singer was dead before help was summoned.

The remainder of the hearing was likely to take a clinical approach, with coroner’s officials, propofol experts and police who interviewed Dr Murray taking the stand.

Judge Pastor said on Friday that prosecutors told him they were ahead of schedule, although he did not indicate when the hearing may end. Prosecutors appeared to be at least halfway through presenting their case.

Defence attorneys rarely present witnesses or their own theories during preliminary hearings. In Dr Murray’s case, they did not make an opening statement and have only hinted at potential arguments as they questioned witnesses.

Dr Murray could face up to four years in prison if tried and convicted.