LAS VEGAS (AP) — A mistrial in the federal prosecution of a family of ranchers who led an armed standoff against government agents prompted Attorney General Jeff Sessions to launch an investigation into the case and renewed calls for a broad review of U.S. attorneys in Las Vegas.

“You can bet that, suddenly, Sessions is asking, ‘Who’s our U.S. attorney in Nevada?'” Rory Little, a professor at the University of California Hastings College of the Law in San Francisco, said Friday. “And somebody says, ‘Well, we don’t have one.’ And they put it on a fast-track.”

Nevada has been without a top federal prosecutor since March, when Sessions, President Donald Trump’s appointee, sought the resignations of 46 U.S. attorneys remaining from Barack Obama’s administration.

The acting U.S. attorney led the troubled prosecution against states’ rights activist Cliven Bundy, his two sons and another man in the 2014 confrontation that stopped a federal roundup of Bundy cattle from public lands.

The case has local defense lawyers urging a review of the U.S. attorney’s office in Nevada. Big federal cases have collapsed in the last 15 years over prosecutors’ failure to share evidence with defendants.

“There’s been a pattern of failure to turn over potentially exculpatory material for more than a decade,” said Robert Draskovich, a defense lawyer involved in a $14 million securities fraud case that was dismissed in 2006 and the failed racketeering prosecution that year against 42 Hells Angels members.

The latter case stemmed from a 2002 shooting in a casino in the resort town of Laughlin between rival motorcycle gangs that left three dead and more than a dozen injured.

This week, Chief U.S. District Judge Gloria Navarro declared a mistrial in the Bundy case. She blamed prosecutors, led by Acting U.S. Attorney Steven Myhre, for “willful” due process violations in failing to properly share evidence that could have helped defense attorneys.

The judge cited 3,300 pages of previously undisclosed FBI and Bureau of Land Management records relating to the standoff that should have been provided to the defense and set a Jan. 8 hearing to decide whether charges should be dismissed outright.

She did not mention a whistleblower memo by a former Bureau of Land Management investigator that alleges widespread bad judgment, bias and misconduct during the planning and operation of the cattle roundup as well as “likely policy, ethical and legal violations” by federal officials.

The investigator, Larry Wooten, said he was removed from the investigation last February after he complained to the U.S. attorney’s office in Nevada.

Justice Department spokesman Ian Prior declined Friday to comment about whether the memo was part of the review ordered by Sessions. He pointed to Thursday’s announcement following the mistrial that Sessions “takes this issue very seriously and has personally directed” a review and report of the case against Cliven Bundy.

Myhre, the acting U.S. attorney, said in a statement through Prior that the Las Vegas office welcomed help “as we continue to evaluate the case in light of the court’s ruling.”

A federal prosecutor for more than 25 years, Myhre assumed the temporary top job in March, when Daniel Bogden departed under Trump’s administration.

Bundy backers have called for months for the administration to scuttle the prosecution, which led to the indictment of 19 people last year.

“This is the fruit of 10 months of lobbying,” said Larry Klayman, a lawyer and conservative activist with close ties to Cliven Bundy but wasn’t allowed to represent him in Nevada.

Klayman has sued in federal court in Washington, D.C., calling for a Justice Department ethics investigation.

Bundy supporters note that most defendants in the case served nearly two years in jail awaiting trials. Seven defendants pleaded guilty to lesser charges or were convicted of some charges.

Only Cliven Bundy remained behind bars during trial, protesting his prosecution and demanding a full exoneration.

Myhre casts the 2014 standoff as an armed uprising, not a peaceful protest over federal control of vast stretches of land in the U.S. West, as the Bundys claim.

He says the Bundys led hundreds of people and a self-styled militia that outnumbered and forced armed U.S. agents to withdraw from rounding up cattle.

Myhre failed to win full convictions of six other men who had guns during the confrontation, including two famously photographed on a highway overpass pointing AK-47-style rifles toward heavily armed agents.

Little, the law professor and a former federal prosecutor, said a Justice Department review of prosecutor performance in Nevada will be distracting, time-consuming and could end careers.

“You’re a long way from discipline. But the immediate impact is very harsh,” he said. “Nothing is worse for a prosecutor than not knowing if they have complied with the rules and knowing that they could be held personally responsible.”