SANDPOINT — A Cocolalla man accused of shooting his son to death last year pleaded not guilty on Tuesday in 1st District Court.

James Michael Costello Sr.’s plea sets the stage for a jury trial on a charge of second-degree murder in September. He remains in custody with bail set at $1 million.

Costello, 72, was originally charged with first-degree murder for allegedly shooting his adult son, James Michael Costello Jr., aboard the converted city bus that served as their home last November.

Bonner County Prosecutor Louis Marshall argued during a preliminary hearing earlier this month that the shooting was premeditated because the elder Costello disabled a surveillance camera on the bus prior to the shooting.

The elder Costello also never summoned help for his son and allegedly attempted to frame another man for the slaying by giving him the murder weapon, a .45-caliber semiautomatic pistol.

Judge Justin Julian ruled that the shooting was more of an impulsive act than a coldly calculated killing.

Audio culled from the video system before it was disabled picked up the younger Costello threatening suicide and ordering his father to retrieve the pistol and shoot him.

The younger Costello is also heard threatening his father’s life and warning him to shut up.

“Get in my face and I will kill you,” the elder Costello warns his son in one of the recording’s final utterances, according to Bonner County Sheriff’s Det. Sgt. Phil Stella.

The killing was not discovered until Nov. 12, after the elder Costello was arrested for driving under the influence and eluding law enforcement in Kootenai County.

The arrest prompted authorities to conduct a welfare check at the bus, which led the discovery of the younger Costello’s body.

While being held at the Kootenai County Jail, a fellow inmate said that the older Costello indicated that his son had been abusive to him and attacked him with a metal bar from a piece of exercise equipment, although he insisted to a sheriff’s detective that his son had not abused him.

Members of a family which allowed the Costellos to park their bus testified that the father and son would occasionally get into alcohol-fueled arguments, but noted that the younger Costello seemed more worked up and agitated than he had been on prior occasions prior to his death.

Keith Kinnaird can be reached by email at kkinnaird@bonnercountydailybee.com and follow him on Twitter @KeithDailyBee.