BONNE TERRE, Mo. — A southern Missouri man appealing his conviction in a live-in girlfriend’s murder has enlisted some unusual character witnesses: former sheriff’s deputies who testified that they planned to arrest another suspect for the crime. Donald “Doc” Nash, 72, was convicted of murder in 2009 in the 1982 slaying of his girlfriend, Judy Lynn Spencer, and is serving a life prison sentence without the chance for parole. The killing remained unsolved until new DNA evidence linked …