The issue that a prosecution was not timely instituted may be raised at any time, but only once, and shall be tried by the court alone. If raised during the trial, a hearing thereon may be deferred until the end of the trial.

The state shall not be required to allege facts showing that the time limitation has not expired, but when the issue is raised, the state has the burden of proving the facts necessary to show that the prosecution was timely instituted.