Rural Ottawa manslaughter case next hearing set April 11

An Iowa man will appear April 11 for a motion hearing in hopes of avoiding a do-over trial in his 2017 manslaughter case from rural Ottawa.

Mason T. Shannon, 48, of Newton, Iowa, and his lawyers appeared at a virtual hearing Wednesday ahead of a potential re-trial for involuntary manslaughter, a Class 3 felony carrying up to five years in prison.

Shannon was initially convicted for his role in the 2017 death of Michael Castelli, of Ottawa, whom Shannon admitted placing in a neck restraint during a struggle outside the Bonnie Plants growing facility. Shannon argued he acted in self-defense.

While awaiting sentencing, Shannon succeeded in getting the conviction thrown out. Visiting Judge William Dickenson voided his guilty verdict based on a conflict of interest at trial. Shannon has since argued he should not have to stand trial again.

Though Shannon struck out in post-trial motions and on appeal, his lawyers submitted Wednesday another motion to dismiss the manslaughter charge. The defense revived allegations the La Salle County State’s Attorney’s Office committed prosecutorial misconduct that has “forever corrupted” Shannon’s case.

“The court’s conscience should be shocked by this behavior and dismissal is the only appropriate remedy,” wrote Douglas DeBoer, one of Shannon’s attorneys, in a 34-page filing that alleged witness and document mishandling.

The Illinois Attorney General’s Office, which entered the case in 2020, has 45 days to reply to the newly-filed motion. An in-person hearing then will be held at 2 p.m. Tuesday, April 11, in La Salle County Circuit Court.