A notorious New Jersey serial killer was arraigned Wednesday in connection with the gruesome 1968 cold case murder of a young New Hyde Park mother at the Green Acres Mall in Valley Stream.

Richard Cottingham, now 75, is serving time in a New Jersey prison for other murders. His alleged victim, Diane Cusick, 23, was found dead inside her car, parked in the mall parking lot on Feb. 16, 1968. Nassau investigators say the cold case homicide was finally solved using new DNA testing technology, and Cottingham faces a potential 25 years-to-life sentence for Cusick’s murder.

“Thank you to everyone who worked on this case. I never thought I’d see this day; I had given up. But all these people got justice for me and for my mother,” said Cusick’s daughter, Darlene Altman, during a news conference following the arraignment on Wednesday.

She was surrounded by Nassau County District Attorney Anne Donnelly, Nassau County Police Commissioner Patrick Ryder, and Det. Steven Fitzpatrick, captain of the NCPD’s homicide squad. Donnelly pledged that her office would bring Cottingham to justice for Cusick’s murder. Chief Jared Rosenblatt, of the Homicide Bureau, is prosecuting the case, and Jeffrey Groder, Esq. is representing the defendant.

According to police, Cusick was a dance instructor at Wakefield Dance Studio, a dance school in Oceanside. She had just finished teaching a class at about 7 p.m. on Thursday, Feb. 15, 1968, and told her parents she was going to the Green Acres Mall to buy a pair of dancing shoes.

“She never returned home,” Donnelly said. “By 10:30 p.m., her father and mother became concerned. They drove to the shopping mall and looked at the parking field that she was known to use.”

Once Cusick’s parents spotted Cusick’s Plymouth Valiant car,…