Kansas City, Kan. ? Prosecutors are arguing for the early release of a man convicted in the 1982 murder of his lover’s husband in Kansas, another strange twist in a tale of crime that took more than two decades to solve.

At a parole hearing Tuesday, Johnson County prosecutors asked a judge to release Mark Mangelsdorf, of Pelham, N.Y., from prison. He has served five years of a 10- to 20-year sentence for bludgeoning David Harmon to death with a crowbar as he lay in bed at his home in Olathe on Feb. 28, 1982.

Harmon’s wife, Melinda Raisch, of Powell, Ohio, was convicted of second-degree murder in the killing and sentenced to 10 to 20 years. Prosecutors say Mangelsdorf and Raisch were having an affair when they decided to kill Harmon to spare Raisch, the “stigma” of being divorced.

Johnson County District Attorney Steve Howe on Tuesday argued for Mangelsdorf’s early release because of a deal former Johnson County District Attorney Paul Morrison made with Mangelsdorf. Morrison had promised to support Mangelsdorf’s release after five years if he did not get in trouble in prison, despite opposition from Harmon’s family.

The victim’s father, John Harmon, said Tuesday that he didn’t know prosecutors would support early parole for his son’s killer.

“I would urge the parole board to disregard this bogus attempt to circumvent the justice system,” Harmon said.

Mangelsdorf, 50, is not guaranteed an early release. The district attorney supported early release for Raisch last year, but the parole board denied that request.

Raisch and Mangelsdorf began an affair in the early 1980s, when Mangelsdorf was a student and Raisch was a secretary at a small Christian college, Mid-America Nazarene College, now MidAmerica Nazarene University.

The affair ended after the killing and the two went on to lead quiet, crime-free lives. Raisch married a dentist in Ohio and had children. Mangelsdorf graduated from Harvard University business school and became a respected businessman. He married twice and had five children.

Investigators reopened the case, and Raisch was charged in the killing after she gave a story different from the one she had told police in 1982. She was convicted of first-degree murder but allowed to plead guilty to second-degree murder in exchange for testifying against Mangelsdorf.

Mangelsdorf’s defense lawyer, Scott Kreamer, said Tuesday that Morrison knew prosecutors had a difficult case against his client and that the district attorney agreed to support early release if Mangelsdorf kept a spotless prison record.

“For 20 years my client worked, married and had children and was an absolute model citizen and still is a model citizen in prison,” Kreamer told the parole board. “There can’t be any doubt that when he gets out he will be a model citizen.”

Mangelsdorf’s family and supporters also pleaded for his release.

Parole board members said they would interview Mangelsdorf next month and they expect to make a decision in the next few months.