Updated

The Texas district attorney prosecuting bikers allegedly involved in a 2015 shootout with police in Waco asked for his office to be recused from the case of a biker scheduled to stand trial Nov. 6.

The biker, Matthew Clendennen, a landscape lighting business owner from Hewitt, Texas, requested earlier this month that the McLennan County District Attorney's Office be removed from his case because of an alleged ongoing federal investigation of the district attorney, Abel Reyna.

Clendennen was among the 177 bikers arrested following the May 17, 2015, shooting that left 9 dead and 20 injured.

Clendennen sought removal after successfully petitioning to have the presiding state district court judge, Reyna's former law partner, removed.

The replacement judge, state district court Judge Doug Shaver, was set to hear testimony Monday including from two assistant district attorneys who work for Reyna and former Waco police officer Sherry Kingrey attesting to the existence of a federal investigation.

A 2013 email from FBI special agent Daniel Brust addressed to Kingrey, FBI agent Fred Rhea and former Waco fire investigator Kevin Fisk that was obtained by The Associated Press refers to the investigation of Reyna, Kingrey said.

In a court filing Thursday, Reyna "categorically" denied the allegations but said that because he testified in an August 2016 pretrial hearing in Clendennen's case — Clendennen's previous attempt to have the district attorney's office removed — he and the office should be recused "to avoid even the mere suggestion of impropriety."

Clendennen originally argued for the removal of Reyna's office because Reyna made himself a witness in the case by drafting the affidavits Waco police used to arrest the 177 bikers on identical charges of conspiracy to engage in organized criminal activity resulting in the deaths and injuries. Of those, 154 bikers have been indicted.

Reyna declined to comment Thursday, citing a gag order in Clendennen's case.

The first trial connected to the 2015 shootout got underway last week in Waco. It was not immediately clear whether the defendant, Christopher "Jake" Carrizal, a locomotive conductor from Dallas, would make issue of Reyna's request to be recused.

If a judge grants it, Clendennen could face a lengthy trial postponement. A new team of state prosecutors would have to be appointed and process evidence the state has presented to defense attorneys, consisting of thousands of photos, hours of video footage and voluminous police documents.

Waco defense attorney Robert Callahan, who is representing a third biker, said that because the bikers all face the same charges, similar motions seeking Reyna's recusal could further delay court proceedings.

"I would expect that we will see 152 more of these motions and 152 more of these recusals, and that taxpayers will read between the lines that there are some real issues at the district attorney's office," he said.