NEW YORK (WPIX) — More than 50 years after the body of 23-year-old Diane Cusick was found duct-taped in the back seat of her car at a local mall, a notorious serial killer from New Jersey will be charged with her murder, sources told WPIX on Tuesday.

Three sources independently confirmed a sealed indictment against 75-year-old Richard Cottingham for Cusick’s 1968 death. Cottingham has been in various New Jersey prisons since 1980 for five other murders.

Sources told WPIX that DNA was preserved from the crime scene in the Green Acres Mall parking lot in Valley Stream, New York, and a sample from Cottingham linked him to Cusick’s murder. However, Cottingham has retained an attorney and plans to plead not guilty, according to sources.

Just last year, Cottingham confessed to the 1974 murders of two teens from North Bergen, New Jersey: Mary Ann Pryor and Lorraine Kelly. He had picked them up on their way to the Garden State Mall in Paramus, New Jersey, he said, and then raped and tortured them at a hotel for three days before drowning them.

Criminal historian Peter Vronsky, author of “American Serial Killers: The Epidemic Years 1950 to 2000,” said Cottingham told him he’s killed between 85 and 100 women. Vronsky and Jennifer Weiss, the daughter of Deedeh Goodarzi, who was brutally dismembered and set on fire inside a Times Square hotel in 1979, have encouraged Cottingham to come clean on his crimes before he dies.

Cottingham was a married father of three, working at Blue Cross Blue Shield insurance firm in Manhattan, New York, and living in Lodi, New Jersey when he was arrested.

Last year, Vronsky said Cottingham “wanted me to locate a particular drive-in. He wanted to know whether that drive-in was in Nassau or Queens.” The Sunrise Drive-In was a popular outdoor movie theatre located next to the Green Acres Mall on Sunrise Highway in the 1960s and 1970s.

Cusick, a dance teacher and divorced mom, was suffocated by a 2-inch-wide adhesive tape that was wrapped around her mouth and neck. She was dressed in a black leotard, a skirt, a red blouse, and white boots. She told her family she was stopping at the mall after work to buy shoes.

Her body was found on Feb. 17, 1968, in the back seat of her car in the mall parking lot. She had been raped before she was killed.

Ever since Cottingham’s arrest, law enforcement in six different jurisdictions in New York and New Jersey have been working on cold case murders they believe are linked to the serial killer.

Retired chief Robert Anzellotti, who worked in the Bergen County Prosecutor’s Office, has extracted six murder confessions from Cottingham over a 20-year period.