From left: Prince, Blanket and Paris Jackson
Michael Jackson's eldest children, Prince and Paris, watched Dr. Conrad Murray unsuccessfully try to revive their father
Now, on the eve of Murray's involuntary manslaughter trial
– which begins Tuesday in Los Angeles – many are wondering whether Prince, 14 or Paris, 13, might testify in the case.
The late King of Pop's children would like to testify, a source close to the family tells PEOPLE, but their grandmother and guardian, Katherine Jackson, feels it would be too traumatic.
"Katherine doesn't want [Prince] to [testify] – she believes it will be too difficult for him," says the source. "But Prince wants to. He's ready to do what he has to do. Prince saw everything. He can establish a timeline."
At the preliminary hearing
earlier this year, a bodyguard testified that, as Murray struggled to revive Jackson, Paris and Prince entered his bedroom. Paris screamed, "Daddy," and started crying.
The family is waiting to hear what the attorneys want to do, the source says. All of Jackson's immediate family members are on a list of key witnesses shared with jurors to avoid possible conflicts of interest. But attorneys in long trials (this one will last roughly a month) sometimes decide as the trial progresses which witnesses to call to the stand.
The family source also reveals that the Jackson clan is not united as to whether Murray should be convicted.
"Half the family believes he's a fall guy and the other half thinks he was negligent," says the source. "Katherine thinks he was negligent."
All of the family members, including Janet, plan to be in Los Angeles Superior Court Judge Michael Pastor's courtroom Tuesday for opening statements, but they probably won't all be present every day, the source adds. Janet will be on tour
in Australia later next month.