A New Jersey inmate dubbed the "Torso Killer" pleaded guilty to a 1968 slaying near New York City and admitted to four other homicides, prosecutors said Monday.
Richard Cottingham - believed to be one of America's most prolific serial killers - admitted to strangling 23-year-old Diane Cusick on Feb. 15, 1968, at the Green Acres Mall in Nassau County, officials said.
In addition to Cusick's case, he also confessed to four other Long Island slayings, officials said.
"Today is one of the most emotional days we've ever had in the Nassau County District Attorney's Office," District Attorney Anne Donnelly told reporters in Mineola.
Cusick had left her job at a children's dance school and then stopped at the mall to buy a pair of dance shoes when the New Hyde Park woman was strangled by Cottingham, authorities said.
"In the case of Diane Cusick, her family has waited nearly 55 years for someone to be held accountable for her death," said Donnelly, who fought back tears at points of a 40-minute meeting with reporters.
Cottingham is in poor health and living out his days in a New Jersey prison, serving life for murders committed there.
The 76-year-old appeared via remote feed from New Jersey and appeared to be wearing a medical gown.
Nassau County investigators said Cottingham could be responsible for as many as 13 homicides in their jurisdiction, but these slayings are the only ones they can positively link him to now.
He's been dubbed the "Torso Killer" due to the savage manner he maimed some of his victims. Cottingham had also been called the "Times Square Killer" for murders he committed in New York City.
Cottingham knew details of the five Long Island slayings that had not been disclosed to the public, and only the killer would have known, prosecutors said.
"These are the five we could be sure that he committed," Donnelly said.
The other four slayings now connected to Cottingham, prosecutors said, include:
The strangulation of Mary Beth Heinz, 21, who vanished on May 5, 1972. Her body was found near a creek in Rockville Centre. "Today we celebrate justice for Mary Beth and my heart is full," sister Jeanne Heinz told reporters. "Honestly I never imagined her case would be resolved."
The body of Laverne Moy, 23, was found on July 20, 1972, and her strangulation haunted loved ones for decades. But son John Moy said Monday: "There's been some dark days behind us but today the sun shines brightly because justice has been served."
Police and prosecutors appealed for the public's help in finding relatives of Marita Rosado Nieves, an 18-year-old from Puerto Rico who strangled on or about Dec. 27, 1973. Her body was found on Jones Beach. Authorities haven't been able to locate living loved ones to share this news. The victim's mother once lived Bayamón, Puerto Rico.
The husband of 33-year-old Sheila Hyman was out shopping and their children away for summer camp when she was found beaten to death on July 20, 1973, in North Woodmere.
The victim's husband, who died in 2004, had long been thought of as a possible suspect.
"But today we can loudly and clearly state for his children and everyone else to hear that he did not murder his wife," Donnelly said. "Richard Cottingham murdered Sheila Hyman."
Hyman's daughter Randi Childs said she originally wasn't going to mention the allegations that haunted her late father - but changed her mind after Donnelly addressed the elephant in the room.
"He was a kind and generous man who loved our mother deeply and who spent too many years living in the shadow of his wife's murder," Childs told reporters.
"There's no reason why he should have been suspected. My poor dad lived with that until the day he died."
This article was originally published on NBCNews.com