COCOLALLA — Unsealed court documents are shedding some light in the first-degree murder case against James Michael Costello Sr.

Costello, 72, is accused of shooting his son, James Michael Costello Jr., inside the converted municipal transit bus on Nov. 10 or Nov. 11, 2018.

The elder Costello was arrested for felony eluding and misdemeanor driving under the influence on Nov. 11. He was found bloodied and bruised and said his son had been hitting him when Idaho State Police arrested him, court records indicate.

James Costello Sr., Bonner County sheriff’s officials have said, made ambiguous remarks during the arrest which prompted them to conduct a welfare check on his son at the bus, which was parked in the 2700 block of Cocolalla Loop Road.

The younger Costello was found laying dead in the narrow aisle inside the bus, sheriff’s Det. Phil Stella said in probable cause affidavit. He had been shot four to five times, with three shots to the chest, affidavit said.

Five .45-caliber casings were recovered near the elder Costello’s bed at the back of the bus, according to court documents. Bullet strikes on interior of the bus indicated shots were being fired from the rear of the bus toward the front. An empty box for a Kahr Arms .45-caliber semiautomatic pistol was also recovered.

Residents of a home 200 feet from where the bus was parked told investigators they had not seen either man on Nov. 10, but had heard the two yelling and cussing each other out on Nov. 9, the affidavit. The racket was sufficient enough to cause one of the residents of the home to tell the two men to stop. A white truck the two traveled in left the property on Nov. 11.

The elder Costello was interviewed while being held at the Kootenai County Jail. He said he was unable to recall much, but conceded that it was “possible” that he shot his son, according to the affidavit.

A week after the shooting, a Bonner County man contacted sheriff’s official to surrender a Kahr .45-caliber ACP pistol after reading news accounts of the deadly shooting. One of the gun’s magazines held two rounds, while the other held seven, court documents indicate.

The man told investigators that the elder Costello gave him the pistol. He noted that James Costello Sr. did not like him and believes he gave him the firearm in order to frame him for his son’s killing, the affidavit said. He added that the elder Costello was known to carry the pistol on a daily basis.

Investigators concluded the shooting was premeditated because a single-camera surveillance camera on the bus was disabled prior to the killing, court records indicate.

Costello is being held in lieu of the $1 million bail at the Bonner County Jail. A preliminary hearing in the case is set for Wednesday.

Although James Costello Sr. is awaiting trial on the Kootenai County charges, a public defender moved for him to be transported to Bonner County so additional evidence which could be utilized in his defense is not lost, court records show.

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