Retired Suffolk police Det. K. James McCready, who famously tricked a teenaged Martin Tankleff into briefly confessing that he killed his parents in 1988, has died of lung cancer in South Carolina. He was 68.

In retirement, McCready enjoyed playing golf and riding his motorcycle, said his son, Brett, 37, of Daniel Island, S.C. He said his father, who died Monday, was relentlessly upbeat.

“He was always a positive person, always reminding me to think positive,” Brett McCready said. “He had a lot of will power.”

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That will power served him well both when he served in the Army in Korea in the 1960s and during a long career with the Suffolk County Police Department, Brett said. Before his decade in the Homicide Squad, McCready was a detective in the narcotics and rackets units as well.

“Being a cop was definitely his favorite thing,” his son said. Besides the work itself, he said his father “loved the camaraderie.”

In 1988, McCready investigated one of Long Island’s most notorious murders, the stabbing and bludgeoning of Seymour and Arlene Tankleff. McCready took their son Martin, then 17, into custody.

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He told Tankleff during his interrogation that Tankleff’s father had briefly regained consciousness at the hospital and said Martin did it. Tankleff said he must have done it but almost immediately recanted.

Tankleff was convicted of two counts of second-degree murder, but an appellate court threw out the convictions after he served 17 years in prison, ruling that a Suffolk judge failed to consider new evidence that others committed the crime.

Retired Suffolk homicide Det. K. James McCready, 60, near his home in South Carolina, Jan. 4, 2008. Photo Credit: Newsday / Andrew Strickler

Tankleff reacted unsparingly to McCready’s death.

“In life, Detective McCready did great harm to me and my family,” Tankleff said. “I hope that in death, he finds peace.”

McCready always defended his work in that case.

“I’ve made mistakes ... [but] I didn’t make any mistakes in this case,” he said in 2008. “I played by the rules, and don’t you use those rules to your advantage sometimes? If anything ever happened in your family, you would wish you had a McCready investigating.”

McCready’s son, like many police officers to this day, said what he did in that case was right.

SCPD Homicide Det. K. James McCready testifies during the Tankleff murder trial at the Riverhead Criminal Court on June 5, 1990. Photo Credit: Newsday / Dick Yarwood

“It was, I think, brilliant what he did,” Brett McCready said.

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Those close to Tankleff expressed sympathy for McCready’s family.

“They’ve suffered a loss,” said Bruce Barket, the attorney who won Tankleff’s freedom. “Hopefully he’s resting in peace. I hope he’s in a better place.”

Barket deposed McCready last year for a pending federal civil rights suit by Tankleff against Suffolk County.

“My sympathy goes out to his family,” said private investigator Jay Salpeter, who built the case that Barket relied on. “On a professional level I think his tactics as a detective tarnished the shield that he was trusted with. Thank God his actions as a detective do not reflect the fine work of other detectives who wear the shield proudly and with respect.”

Retired Suffolk police Det. K. James McCready at his home in Little River, South Carolina, on Aug. 12, 2004. McCready, who famously tricked a teenaged Martin Tankleff into briefly confessing that he killed his parents in 1988, died Monday, Dec. 28, 2015, in South Carolina. He was 68. Photo Credit: George R. Lees

In an unrelated case, McCready was later charged with robbery and assault while a detective, but was acquitted. His defense attorney then, Thomas Spota, is now the district attorney. Spota did not respond to requests for comment.

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The Suffolk County Police Department declined to comment.

He lived in Huntington before he moved to South Carolina, and his wake and services will be on Long Island.

In addition to his son, he is survived by his wife, Terry McCready; a brother, Tom McCready, of Smithtown; sisters Margaret Corry of Huntington and Eileen Treder of Palm Coast, Fla.; and a granddaughter.

Visitation is 2 to 4 p.m. and 7 to 9 p.m. Sunday at M.A. Connell Funeral Home, Huntington Station. Services will be 9:30 a.m. Monday at St. Hugh of Lincoln Church, in Huntington Station.