Adam Fox said he would invoke the fifth amendment if he was brought in to testify.
He’s currently serving a 16-year sentence in Colorado after being convicted in the kidnapping plot last year.
Three men are set to go on trial Aug. 23 in Antrim County’s 13th Circuit Court for what state prosecutors say was their role in the plot.
One of the men, Eric Molitor, sought to have Fox testify as a defense witness.
The other two defendants are brothers Michael and William Null.