Actress Sharon Tate, the pregnant wife of director Roman Polanski, and three guests, coffee heiress Abigail Folger, her boyfriend, writer Wojciech Frykowski, and hairstylist Jay Sebring, and Steve Parent, a teenager visiting the caretaker on the Los Angeles property, were killed on Aug. 9, 1969. The next day, Rosemary and Leno LaBianca, a grocery executive, were killed in their home.
Manson, originally sentenced to death, has been turned down for parole 11 times, ABC News reported. Members of his "Family" convicted of the murders also remain in prison in California.
"When you consider what they did, they didn't have any remorse," Larry Sheely, who was 23 when he served on the jury at the trial in 1970, told ABC. "It was kind of like entertainment for them."
For the past 20 years, Manson has been incarcerated in the state prison at Corcoran in a unit for inmates who might be at risk in the general population. Other inmates in the unit include Sirhan Sirhan, who assassinated Sen. Robert Kennedy in 1968 and Juan Corona, convicted in 1971 of killing 25 migrant farm workers.