Cult-leader Manson, buddy Charles "Tex" Watson and two of his infamous "Manson women" -- Patricia Krenwinkel and Atkins -- were sentenced to death for the Tate murders and the slaying of grocery store executive Leno LaBianca and his wife Rosemary on Aug. 10, 1969. A third woman, Leslie van Houten, was convicted along with the others and sentenced to death on two counts of murder for her role in the LaBianca murders.
Their sentences were later commuted to life in prison when California temporarily abolished the death penalty in 1972.
Sharon Tate's husband at the time, movie director Roman Polanski, declined to comment on the possibility of Atkins' release.
Anthony DiMaria, nephew of Jay Sebring, a hairstylist to the stars who died as he tried to protect Tate and her unborn child, said he will once again make the trek from Las Vegas to California in hopes of keeping his uncle's murderers out of society.
"She's more than a Manson follower," he said of Atkins. "She's a mass murderer."
Paroling Atkins because she is dying of cancer -- a disease he called "fate" -- would send the wrong message, especially given Manson's dark following as some kind of anti-hero, DiMaria told ABCNews.com.
"Like it or not she and these crimes have had a huge impact, obviously on our family but also culturally," he said.
Atkins has spent most of the last 38 years at the California Institution for Women in Corona, Calif., the same facility that houses Krenwinkel and van Houten. She was moved to Chowchilla last year after being hospitalized.
Terry Thornton of the California Department of Corrections and Rehabilitation said Atkins has been an active inmate with a "well-documented record" of volunteerism and participation in events and groups dealing with personal growth, religion, substance abuse, self-help and fundraising.
She's also earned over the years "above average to excellent work performance ratings," Thornton said, and has held a variety of jobs working in laundry, maintenance and the yard crew as well as positions as a teacher's aide, a clerk and a porter.
Thornton said Atkins also logged five rules violations in her 38 years in prison, the most recent in March of 1993. She did not have specifics about the violations.
She's also been married twice while behind bars. Her second husband, James Whitehouse, has become her most vocal supporter and pleaded on her behalf at Wednesday's parole hearing.
When the parole board considered a motion for Atkins' compassionate release last summer, Whitehouse questioned the point of keeping Atkins in prison in her current condition.
"It occurred to me that compassion's not something you earn," he said in July 2008. "It's something that every single person should have merely by means of the fact that they're human beings."
Whitehouse described his wife's grim physical condition.
"At this point, when she can't sit up in bed, she literally cannot sit herself up in bed, she suffered paralysis on her right side, she's lost her left leg. Her left arm, her only appendage she can still use, is debilitated to the point that she literally can't snap her fingers," he said. "She can say yes most of the time. Sometimes she can say no. She can say random words. She can put sentences together three or four times a day, but that's the extent of it."