During the course of an interview, Lowe said, investigators determined that Noble had disposed of the rifle believed to have been used in Sunday's shooting death of Clinton police Officer Gary Michael.
William Noble, 35, has been charged with tampering with evidence in felony prosecution.
Authorities say he shot and killed Michael Sunday night during a traffic stop.
Ian McCarthy, the man with a long criminal history in New Hampshire who is accused of shooting to death a Clinton, Mo., police officer, will plead innocent to the charges today, according to his public defender.
Highway Patrol Sgt. Bill Lowe says a passerby saw McCarthy on the side of the road Tuesday evening and alerted police.
A $25,000 cash only bond has been requested.
The officer told him he knew the answer to his own question. He eventually changed his story and acknowledged that McCarthy asked him to buy the rifle for him.
Police asked Noble if he knew where the gun now was.
They say Noble told them he arrived home on Monday, Aug. 7th, at about 2:00 a.m., and found the rifle leaning against the inside doorway of his house.
Ian McCarthy appeared via video at his arraignment Friday at the Henry County Courthouse in Clinton. He took the two officers to the creek Thursday, where they recovered a rifle that "meets the description and appears to me to be the weapon used in the murder", according to the probable cause statement. He said he panicked, told his wife he was taking the trash out, and drove north out of town with the gun.
An officer walked to the edge of the water near NW 300th Road and NW 131st Road and spotted the stock of a weapon under water.
Acquaintances of a man charged in the killing of a western Missouri police officer say he spent most of his time at home playing video games, didn't have a job and rarely socialized with others.
The Highway Patrol says Officer Michael had stopped a vehicle for a registration violation. The bullets that hit Michael ultimately killed him.