Mass murderer Charles Manson recently made headlines when he obtained his marriage license to marry his 26-year-old groupie Afton Elaine Burton, also known as “Star,” and now one of the victim’s sisters is speaking out calling the impending nuptials “ludicrous” and “insane.”

According to ABC News, Manson and his followers Leslie Van Houten, Patricia Krenwinkel, and Susan Atkins were convicted in the gruesome slayings of Sharon Tate, the pregnant wife of director Roman Polanski, and four others on the night of August 9, 1969. Two others, Leno and Rosemary LaBianca, were killed the next night.

Sharon’s sister Debra Tate has spent the majority of her adult life making sure that Manson remains in prison, and is outraged that he has received permission to get married.

Debra explained that Burton believes Manson is leading a movement to save the environment. Burton even wore a shirt while speaking to the Associated Press that read ATWA, which stands for air, trees, water, animals.

“I wonder how long it will take for her to figure out this is just a con,” Tate said. “It makes me wonder what is missing in her life that she would want to marry an 80-year-old man. Is she a victim? Is she mentally deranged?”

Since Sharon’s death, Debra has made sure to attend every parole hearing Manson has, arguing on behalf of her sister on why he and his followers should remain in prison.

“I don’t want any more heinous actions by another family like his because of something I didn’t do,” she said.

Prison officials explained that Manson and Burton will be allowed to have a private ceremony in the prison. They are allowed to invite ten outside guests, and will be allowed to kiss and hold hands during the ceremony. While Burton is allowed to wear whatever she likes, Manson will be wearing his prison scrubs. Manson will not be restrained during the ceremony, but will not be allowed any physical contact after the ceremony is over.