08/27/2014 AT 04:15 PM EDT
08/27/2014 AT 09:00 AM EDT
Between Aug. 8 and 10, 1969, the bizarre, cultish group known as the Manson Family committed a series of gruesome murders near Hollywood, California, that claimed seven lives, including those of director Roman Polanski's then-pregnant wife, Sharon Tate, and coffee heiress Abigail Folger.
While other murderers my have been just as heinous, Manson and his "Family" still manage to haunt the American consciousness nearly 50 years on.
Manson, who made a notorious 1969 court appearance with an "X" carved into his forehead – to tell authorities, "I have X'ed myself out of your world" – was denied parole for the 12th time in 2012, after telling a prison psychologist
, "I am a very dangerous man."
Of the other members of the Manson Family, Lynette "Squeaky" Fromme may be the best-known, having attempted to shoot President Gerald Ford in 1975. She was released on parole in 2009.
Family member Bruce Davis was granted parole in March 2014 after his 28th parole hearing; the decision was later reversed by California Governor Jerry Brown in August
, the third such instance of an act by a California governor.
Other members of the family either have been killed, died in prison or are still serving time.
Sharon Tate's sister Debra tells PEOPLE
that she's often reminded of the horrible events of 1969 while helping other victims or survivors of violent crimes, or attending parole hearings for members of the Family.
"They're nothing special. They're just little creeps," she says about Manson and his followers. "They're nothing that should be regarded in any way, shape or form. What should be regarded are the people that were lost. They were truly magnificent people."
For more about the murders and the lives lost that fateful night, pick up this week's issue of PEOPLE, on newsstands Friday