A 75-year-old serial killer serving a life sentence in New Jersey state prison for murdering women over a decades-long span now is accused of strangling a woman in a Long Island mall parking lot more than 50 years ago, Nassau County prosecutors say.

Richard Cottingham was indicted by a grand jury in the February 1968 killing of Diane Cusick, prosecutors said Wednesday. Cusick was a 23-year-old dance teacher and mother of one when she was found beaten, raped and duct-taped in her car in Valley Stream's Green Acres Mall parking lot that year. It was two days after Valentine's Day.

Cottingham allegedly pretended to be a security guard or police officer to get Cusick -- and others -- to go with him, Det. Captain Steven Fitzpatrick said at a news briefing. Fitzpatrick said authorities had reviewed all homicides of women in the area at the time Cusick was killed and may have found other cases linked to Cottingham.

They have at least five open cases they have submitted for DNA testing, he added.

Cottingham pleaded not guilty to a second-degree murder charge in Cusick's case on Wednesday and was remanded. He faces another life sentence if convicted.

“Diane Cusick, a 23-year-old mother, called her parents on the night of February 15, 1968, to tell them she was going to the mall to purchase shoes. She never returned home," Nassau County District Attorney Anne Donnelly said in announcing the indictment. "Cusick was allegedly bound and murdered by Richard Cottingham."

"It was only through advances in DNA technology that the NCDA and our partners at the Nassau County Police Department, could solve this 54-year-old cold case and identify a suspect in Ms. Cusick’s tragic death," Donnelly added. "We make a promise to her surviving daughter today: we will bring her mother’s killer to justice."

Cusick had gone to the mall the day she died to get some dance shoes. Her parents reported her missing when she didn't come home. They were the ones to find her car at the mall parking lot -- and they were the ones to find her body in the backseat.

But it was Cusick's daughter, Darlene Altman, who stood alongside law enforcement Wednesday as they announced the indictment.

"I never thought I would see this day but all these people got justice for my mom," daughter Darlene Altman said. "It was overwhelming to see him on video in court with a dead stare."

One of New Jersey's most notorious serial killers, Cottingham was nicknamed "The Torso Killer" because he was known for dismembering his victims, according to NorthJersey.com. He has admitted to killing at least a dozen women since the 1960s.

Most recently, Cottingham pleaded guilty last year in New Jersey to the 1974 murders of two teenage friends who went to the mall one day for bathing suits and never returned.

The teenagers, 17-year-old Mary Ann Pryor and 16-year-old Lorraine Marie Kelly, were among at least a dozen victims linked to Cottingham over the years. He admitted to murdering nine women in the 1960s and 70s but the death toll is thought to be higher.

In the early 1980s, Cottingham was convicted of killing five women — three in New York and two in Bergen County — and in 2010, he confessed to killing a woman in northern New Jersey in 1967. He has been jailed since 1981.

Cottingham has claimed to be responsible for up to 100 murders. Pryor and Kelly were found five days after they went missing — their nude, battered bodies discovered facedown in the woods of northern New Jersey. Kelly was reportedly found with a beaded bracelet and a necklace that read “Lorraine and Ricky,” a reference to her boyfriend. Pryor was discovered with a gold cross, a gift from her godfather.