ST. LOUIS (AP) — A former U.S. attorney and circuit judge was appointed Wednesday as special prosecutor in the case against a St. Louis couple who waved guns at racial injustice protesters last summer.

Circuit Judge Steven Ohmer chose Richard Callahan to prosecute Mark and Patricia McCloskey, who have pleaded not guilty to unlawful use of a weapon and evidence tampering.

Callahan was the U.S. attorney in St. Louis from 2010 to 2017, and was a circuit judge and a prosecutor in Cole County.

St. Louis Circuit Attorney Kimberly Gardner was disqualified from the case in December after a judge ruled she created an appearance of impropriety by mentioning the McCloskey case in fundraising emails before the Democratic primary in August.

Callahan said Wednesday from his Jefferson City home that he has prosecuted politically charged cases in the past, The St. Louis Post-Dispatch reported.

“I am going to approach it the same way I’ve done anything in the last 49 years — start with a blank slate, follow the evidence and see where it takes me,” said Callahan, who is 73.

The McCloskeys are accused of waving guns at the protesters as they walked by the couple’s mansion in a private neighborhood on the way to the home of former Mayor Lyda Krewson. They are also accused of altering the pistol that Patricia McCloskey was holding that day.

The McCloskeys were praised by President Donald Trump and other conservatives but criticized by some for the incident that happened amid nationwide protests following George Floyd’s death in Minneapolis. Missouri Gov. Mike Parson has vowed to pardon the McCloskeys if they are convicted.