Prince Jackson, 16, said he saw his father often get upset on the phone with AEG Live Chief Executive Officer Randy Phillips, but was unable to stand up for himself in disagreements.
"He would get off the phone, he would cry sometimes," Prince told jurors in a Los Angeles courtroom about his father. "He would say, 'They're going to kill me. They're going to kill me.' ... He was like my grandma. He was too kind to fight anybody."
Small parts of a video recording of Prince and younger sister Paris' deposition recorded months earlier had been played in court last week, but Prince was the first Jackson family member to testify in person at the trial.
Prince, who took the stand four years and one day after his father's death, was 12 when Jackson died at age 50 in Los Angeles from an overdose of surgical anesthetic propofol ahead of a series of comeback concerts in London in 2009.
The "Thriller" singer's mother, Katherine, is suing privately held AEG Live, which was promoting Jackson's "This Is It" concerts, for negligence in hiring Dr. Conrad Murray as his personal physician.
Murray was caring for the singer as he prepared for the shows and was convicted of involuntary manslaughter in 2011 for administering the propofol that killed Jackson.
Prince, wearing a dark suit and tie, showed little emotion while testifying until he described his father's death, which was the first time any of Jackson's children have spoken publicly about it.
The teenager said he and his two younger siblings - sister Paris and brother Prince Michael II, also known as Blanket - were at their rented Los Angeles home when they heard a scream from the home's second level.
"I ran upstairs and I saw Dr. Conrad doing CPR on my dad on the bed," he said. "My dad was hanging halfway off the bed, and his eyes were rolled back in his head."
He added: "My sister was screaming the whole time, saying she wants her daddy. I was waiting at the bottom of the stairs, crying, waiting for the ambulance."
'IT HURT A LOT'
Prince, his voice cracking with emotion, said Murray told them in a hospital waiting room that Jackson had a heart attack.
"Sorry kids, your dad's dead," Prince remembered Murray telling him.
AEG Live has said it did not hire or supervise Murray and argues that Jackson had prescription drug and addiction problems for years before entering into any agreement with the company.
AEG Live also has said they could not have foreseen that Murray posed a danger to Jackson.
Katherine Jackson, 83, along with the singer's three children are listed as plaintiffs in the case. The trial began in late April and is expected to last for another month.
Earlier witnesses for the plaintiff have testified that Jackson had grown so weak he had difficulty executing dance moves and recalling song lyrics, and that Murray's monthly salary from AEG Live would be a conflict of interest in his care of the singer.
Prince also testified that Jackson's death has taken an emotional toll on the children.
"I have a hard time sleeping," the teen said. "I became emotionally distant from a lot of people."
Paris, 15, who has been hospitalized after an apparent suicide attempt earlier this month, has taken the loss of her father the hardest, Prince said.
"I think out of all of our siblings, she was probably hit the hardest because she was my dad's princess," he said. "It hurt a lot and she definitely is dealing with it in her own way."
Following Prince's testimony, the Jackson family's attorney, Brian Panish, said at a news conference outside the courthouse that Prince had answered questions consistently and credibly.
"He is a nice, bright young man who has a great future and I think that's because of the father who raised him," Panish said.
The attorney added that Jackson's youngest son, Blanket, will not be summoned in this case, and a decision is still being made on whether Paris will be called up to testify.
