A former student body president and Pelham resident pleaded guilty in a Kansas City courtroom Tuesday to killing a college secretary's husband in 1982. Prosecutors say Mark Mangelsdorf, now 45, was having a romantic relationship with Melinda Raisch when they conspired to kill David Harmon. Harmon was bludgeoned to death in his bed. Harmon?s wife and Mangelsdorf have long been considered suspects in the murder. Mangelsdorf, who hired a high-profile attorney to defend him at his trial, decided to accept a plea offer from the prosecutor when he saw the evidence against him. In exchange for his guilty plea, Mangelsdorf agreed to a sentence of 10 to 20 years in prison. Last May, Raish was found guilty of killing her husband as well as conspiracy to commit murder. Prosecutors say they will offer her the same deal as Mangelsdorf.