Federal prosecutors investigating the suspected plot to kidnap Michigan Gov. Gretchen Whitmer are asking for more time to build a case, citing the finding of bomb-making materials.

Adam Fox, a west Michigan man accused of steering the plan, and five other men are in custody in connection to a plot to kidnap the governor as a means to overthrow the state government. Whitmer, a Democrat, has been criticized for her aggressive pandemic lock-down policies in a state that went to President Donald Trump in the 2016 election.

Assistant U.S. Attorney Nils Kessler in a court filing Monday called for a 40-day extension for seeking indictments on the accused, citing new evidence in the investigation, the Detroit Free Press reported.

"Firearms and explosive device components were recently recovered, and must be analyzed to determine whether charges under the National Firearms Act, explosives or anti-terrorism statutes are warranted," Kessler said.

The attorney added that the FBI has collected “hundreds of hours” of recordings from a confidential source and undercover agents that need to be examined. Fox, according to a federal affidavit, was previously quoted as saying Whitmer was a “tyrant” with “no checks and balances.”

Authorities thwarted the group's kidnapping plot earlier this month. Kessler says authorities were unable to review all evidence prior to the arrests because the accused were suspected of carrying out their plans before Election Day.

The six accused men, including Fox, are entitled to a grand jury trial within 30 days of the original charges. If relief is granted to Kessler, the deadline would be extended to Dec. 16. Eight other men face several related charges in the state for the alleged participation.

Nine of 13 members of Michigan right-wing militias charged with a plot to kidnap the state's governor, Gretchen Whitmer (L-R, top to bottom) Michael Null, William Null, Eric Molitor, Shawn Fix, Ty Garbin, Brandon Caserta, Kaleb Franks, Adam Fox, and Dani Nine of 13 members of Michigan right-wing militias charged with a plot to kidnap the state's governor, Gretchen Whitmer (L-R, top to bottom) Michael Null, William Null, Eric Molitor, Shawn Fix, Ty Garbin, Brandon Caserta, Kaleb Franks, Adam Fox, and Daniel Harris. Photo: Antrim County Sheriff's Office