Osage County Prosecutor Amanda Grellner will dismiss cases and not pursue others after finding improper actions that occurred while Osage County Sheriff Michael Dixon was in office.
The number of cases could total more than 100.
Lt. Ron Dishman, the chief deputy of the department, resigned in August after replacing Dixon as sheriff in May.
Osage County commissioners appointed former Sheriff Carl Fowler, who agreed to serve until a new sheriff is elected in November.
"Upon taking office, Sheriff Fowler asked the Missouri Highway Patrol to do an independent investigation into the integrity of the evidence contained within the evidence room of the Sheriff's Department," Grellner said. "The catalyst for this was the state of the evidence room, lack of documentation for the evidence contained therein and the number of people that had access to evidence room during Dixon's tenure."
Grellner said the investigation found not only did multiple people have access to evidence room, but the door was left open and unattended on a number of occasions. Also, there were a number of items not properly documented if at all, along with evidence in a poor state and not secured or tagged properly.
"I met with members of the Division of Drug and Crime Control of the Patrol after their investigation, and they determined they cannot verify or substantiate the integrity of the evidence contained within the evidence room," Grellner said. "As a result, I am obligated under two U.S. Supreme Court cases to not only disclose this breach but to act accordingly knowing that the integrity of the evidence contained with cannot be verified."
Grellner estimated the affected cases could number "100 or better" and largely involve drug matters but not any homicides. They date back to January 2013 when Dixon took office as sheriff.
"I am disappointed that proper care was not taken within the evidence room after Sheriff Dixon took office as it will result not only in cases being dismissed but also guilty pleas being set aside," Grellner added.
Dixon didn't file for re-election earlier this year, and Dishman was not one of the four candidates running to succeed the first-term sheriff. Mike Bonham won the August Republican primary, and Chris Albert won the Democratic primary.
Dishman had filed to run as an Independent candidate for sheriff in November's general election, but Grellner asked the Missouri Highway Patrol to investigate his residency. She confirmed the investigation found Dishman's real and personal property taxes were assessed in Phelps County. State law requires sheriff candidates to be residents of the county in which they are running for more than one year before filing.
Dishman took his name off the ballot.
Dixon made a brief appearance earlier this month in Boone County's associate circuit court and will be back in court Nov. 4 for a preliminary hearing.
He was charged April 8 with being intoxicated and unlawfully pointing a weapon at another person in the Hitchin' Post, a Hartsburg bar.
At the November hearing, the state has to present enough evidence to convince the judge a crime was committed and there's a reasonable likelihood Dixon committed it.
If she agrees, then the case would be sent to the circuit court - and a different judge - for a trial.
At the time he was charged, Dixon still was Osage County's sheriff, and a felony conviction also would have resulted in his losing his required peace officer's license and job.
But he did not file for re-election, and resigned as sheriff on May 26.
Dixon pleaded guilty July 1, 2014, to a misdemeanor harassment charge involving incidents in Belle in 2012 and 2013.
Special Prosecutor John Beger had charged Dixon with a felony and several misdemeanors, all reportedly connected with a female Belle police officer Dixon had supervised when he was the city's marshal, before becoming Osage County sheriff on Jan. 1, 2013. He was placed on two years supervised probation.
"Our entire justice system relies on the integrity of not only law enforcement but the collecting and handling of evidence, and as a result of this breach and mishandling, I am left with no choice but to act as the law requires in order to attempt to maintain that level of integrity that people are entitled to," Grellner said.