Area mansentencedin slayingNorman Dakin, 34,Middletown, was sentenced today by Butler County Common Pleas Court .Judge Fred B. Cramer to an indeterminate term , of one-20years in the statepenitentiary for the shooting death of a Middletown bartender three years ago.Dakin pleaded guilty to first degree manslaughter. The defendant originally had been charged with first •degree murder.John F. Holcomb,prosecuting attorney, said the manslaughter plea was accepted because the case was three years old and some evidence was unavailable.Victim of the shooting was John Duhamel, a bartender at Gene's Bar in Mayfield, a Middletown suburb. He was shot to death Dec. 15, 1370.The killing remained unsolved until last September when Dakin was picked up in Houston, Tex, on a bunglary charge. During an interrogation, Dakin reportedly admitted the shooting in Middletown, the prosecutor's office said.