La Toya Jackson wants Dr Conrad Murray to be charged with premeditated manslaughter.
The physician is set to be charged for involuntary manslaughter relating to the death of La Toya’s pop superstar brother Michael last June, but she doesn’t believe it is enough.
She said: "He should have been charged with premeditated."
If found guilty, premeditated manslaughter carries a more serious sentence.
Michael’s father Joe also believes Murray should receive the more serious charge.
The family’s lawyer, Brian Oxman, said: "I spoke to La Toya Jackson, she wants justice for her brother.
"She is upset and has been upset about Michael's death. I spoke to Joseph Jackson. He wants justice for Michael. They are not angry, they are not vindictive, they are heartbroken. They do not think that the charge of involuntary manslaughter is appropriate. They feel that it is a slap in the face. As to exactly what they would like to see, they would like to see justice."
The family’s reaction comes as authorities ready themselves to charge Dr Murray after a lengthy police investigation.
According to reports, the physician is set to hand himself in to Los Angeles police tomorrow morning.
Michael died suddenly last June aged 50 as he was preparing for 50 sell-out concerts at London’s O2 Arena.
Dr Murray - who was the ‘Thriller’ star’s personal doctor - told detectives he had given him the general anaesthetic Propofol and two other sedatives to help him sleep.
The Los Angeles County coroner's office ruled the singer's death was homicide by drug overdose.