A second man, William Noble, 35, of Clinton, was charged Thursday with felony tampering with evidence after prosecutors alleged he supplied the weapon used to kill Michael.
Authorities say he shot and killed Michael Sunday night during a traffic stop.
He is scheduled to be arraigned on Friday on charges of first-degree murder and armed criminal action.
Highway Patrol Sgt. Bill Lowe says a passerby saw McCarthy on the side of the road Tuesday evening and alerted police.
He also was wanted at the time of his arrest on a warrant out of Johnson County, Missouri, issued in 2015 for unlawful possession of a firearm. Police say Noble acted like he was visibly upset and faked crying.
The Henry County prosecutor says that Noble knew the rifle was used in a crime and attempted to hide it.
Noble initially told two officers who visited his home on Thursday that he bought the rifle and sold it to McCarthy. Police say they told Noble that he already knew the answer to that question. However, he then changed the story and admitted he bought the gun for McCarthy because he was asked to.
Police asked Noble if he knew where the gun now was.
Noble saw the safe was damaged, began acting "suspicious", and asked what type of gun was used in the murder.
Noble told the officers he "panicked" when he returned home on Monday - the day after the shooting - and found the rifle leaning against an inside doorway, the statement said.
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.
Michael's funeral will be held Saturday at 11 a.m.in Clinton. He didn't seem to have worked since arriving in Clinton about four years ago. A news release says others may be implicated in the case as the investigation continues.
McCarthy was taken to a Kansas City area hospital for treatment and then was taken into custody at the Henry County jail. The bullets that hit Michael ultimately killed him.