The LAPD proposed granting Susan Atkins prosecutorial immunity in return for her testimony that could convict Charles Manson. Lead Prosecutor Vincent Bugliosi objected, saying "We don't give that gal anything!" In the end, the prosecution offered not to seek the death penalty in return for her trial testimony. Atkins, after testifying before the Grand Jury, refused this offer. Atkins was convicted of first-degree murder and sentenced to death in 1970. However, the California Supreme Court declared the state’s death penalty unconstitutional, and her sentence was reduced to life imprisonment.
Van Houten's first-degree murder conviction was overturned by a state appellate court when Judge Older mistakenly failed to grant Van Houten’s motion for a mistrial following the disappearance of her attorney, Ronald Hughes. The jury was not able to reach a verdict in her first re-trial. In 1978, she was tried a third time; she was convicted of first-degree murder after the jury rejected her defense of diminished capacity resulting from use of hallucinogenic drugs.
Patricia Krenwinkel’s attorney provided only a weak defense. Krenwinkel’s fingerprints were found inside the Tate home.
Charles “Tex” Watson fought extradition to California long enough that he was tried separately from the others involved in the murders. His defense attorneys contacted eight psychiatrists to try to prove that Watson was either insane at the time of the murders or that he suffered from severely diminished capacity. Watson tried to portray himself as Manson's unthinking slave when he was on the witness stand. The jury ultimately convicted Watson of first-degree murder.
The major turning points in the trial came when members of the Family, such as Paul Watkins came forward to testify, and when Susan Atkins described to her cellmates in detail the crimes committed. The cellmates later made authorities aware of the confession.
Charles Manson was originally convicted and sentenced to death, but the 1976 California Supreme Court decision declared the state’s death penalty law unconstitutional. Manson has been denied parole twelve times since his conviction; the most recent instance of this was in 2012.