They questioned Dan Chappel's motivation to get inside a band of anti-government extremists and the key steps he took to gather evidence.
Chappel was cross-examined for hours as lawyers pressed their theme that any 2020 scheme against Democratic Gov. Gretchen Whitmer was driven by agents and operatives.
Adam Fox and Barry Croft Jr. are on trial for the second time on conspiracy charges.
A federal jury in Grand Rapids, Michigan, couldn’t reach a unanimous verdict in April but acquitted two other men. Croft is from Bear, Delaware, and Fox is from western Michigan.