A man from Sigourney accused of killing his girlfriend’s four month old son has pleaded not guilty.  21-year-old Johnny Dale, Junior is charged with first degree murder in the June death of Kane Bruns.  According to the criminal complaint, Dale was watching Bruns when the boy’s mother went to work. When she came home, the baby had a bruise on his forehead and wouldn’t wake up.  Doctors told investigators Kane had suffered brain and spinal cord injuries consistent with child abuse.  Dale admitted to investigators he had grown frustrated with the baby and bounced him on an air mattress in an attempt to get him to sleep.  Kane later died at a Des Moines hospital.  Dale remains in custody in the Mahaska County Jail on a million dollars bond.  His trial is scheduled to start November 19 in Oskaloosa.