Michael Jackson's personal assistant spoke today of the "frantic" scenes as doctors battled to save the star's life -- and how medic Conrad Murray suggested a cover-up minutes after his death.

On the second day of a long-awaited manslaughter trial, the court also heard that Murray claimed repeatedly that the pop icon was in good health, in the days and weeks before his death on June 25, 2009.

The most gripping testimony though came from Michael Amir Williams, Jackson's personal assistant for two years leading up to his death aged 50 from an overdose of the powerful sedative propofol.

He recalled the phone call from Murray alerting him that something had gone terrible wrong.

"He said 'Where are you?' I said: 'I'm downtown.' He said 'Get here right away, Mr. Jackson had a bad reaction. Get here right away' .. He said 'Get somebody up here immediately," Williams told the LA Superior Court.

When he arrived at Jackson's rented mansion in the plush Holmby Hills district 30-40 minutes later, "It was real frantic. I got there when the gurney was coming down," he said.

The trial opened in Los Angeles Tuesday, when prosecutors laid out their case that Murray was guilty of "gross negligence," while the medic's lawyers said the drug-addicted star effectively caused his own death.

The first day saw chilling images of Jackson's dead body and heard a haunting audio recording of the heavily-drugged singer talking on the phone only weeks before his death.

But it also heard evidence that Jackson, while giving cause for health concerns a week or two before he died, was in reasonable form in his last days, rehearsing for an ill-fated series of comeback shows in London.

His assistant echoed that Wednesday, recalling the last rehearsal at LA's Staples Center on the night of March 24. "He was in good spirits," he said, adding of Jackson's last time on stage: "I thought it was amazing."

But things went wrong overnight, when Murray allegedly gave Jackson a series of drugs to help him sleep -- the doctor's lawyers claim the star took more by himself -- before finding him not breathing after going out the bathroom.

The next day, as paramedics rushed Jackson to the nearby UCLA hospital, Williams recounted how the media were already in hot pursuit, forcing him to shield the star's children Prince Michael, Paris and Blanket from view.

"I took off my jacket and covered them up one by one, and took them inside the hospital. There were cameras everywhere," he said.

After Jackson was pronounced dead, he recounted what he called an "odd" conversation with Murray. "I was in a hallway. We were making small talk about how horrible this is."

Then, "he said that there's some cream in Michaels room .. that he wouldn't want the world to know about. And he requested that I or someone give him a ride back to the house to get it."

He refused the request, saying he pretended that he did not have his car keys. "I was emotional. There was a lot going on. that was the last thing I really was thinking about," he said.

Pre-trial hearings heard evidence that Murray asked for other medicine and equipment -- reportedly including bottles of propofol -- to be removed from the room before police arrived.

The state of Jackson's health is central to the involuntary manslaughter trial, which is due to last five weeks.

A lawyer tasked with drawing up Murray's $150,000-a-month contract to look after Jackson during the planned "This Is It' London shows said the doctor told her repeatedly that Jackson was fine.

"Dr. Murray told me repeatedly that Michael Jackson was perfectly healthy, in excellent condition," attorney Kathy Jorrie testified, adding Murray told her "Don't worry about it, he's great."

Murray, 58, faces up to four years in jail if convicted by a jury of seven men and five women.