Authorities are continuing to investigate the shooting of Gerald Ruskamp, 65, of rural Wisner following his death last September.
The Nebraska State Patrol is investigating the incident as a possible homicide.
Ruskamp's son, 30-year old Carl F. Ruskamp is named as a suspect.
Earlier this year, an investigator with the Nebraska State Patrol indicated there is probable cause to believe the younger Ruskamp is responsible for his father's death. A warrant was signed in late February requesting a DNA sample. This was provided on March 16.
Carl Ruskamp has not been charged in connection to the incident.
At the time of the shooting, Carl and Duane Ruskamp were arrested on suspicion of manufacturing a controlled substance. During an interview at that time, Duane voluntarily provided a DNA sample to authorities. Carl refused to provide a DNA sample at that time.
Although Carl Ruskamp has not been charged in connection with his father's death, he has been charged with manufacturing a controlled substance, which is punishable by up to 20 years in prison. He has since been ruled incompetent to stand trial and has been housed at the Nebraska Department of Corrections' Reception and Treatment Center in Lincoln.
Following a hearing early this month in District Court, Judge Mark Johnson ordered Carl Ruskamp to be put on a waiting list for admission to the Lincoln Regional Center, where he will undergo treatment to restore his competency.
