The April 19 letter urges Kevin Techau, the U.S. attorney for the Northern District of Iowa, to "rectify the injustice" done to Rubashkin, who was convicted in 2009 of bank fraud and money laundering charges in the wake of a historic raid by immigration agents at his family's Postville meatpacking plant, Agriprocessors.

The letter comes as defense attorneys detailed new evidence in a March filing suggesting that prosecutors knowingly allowed "false and misleading" testimony at a sentencing hearing that U.S. District Judge Linda Reade relied on in handing down the lengthy sentence. Among the signers accusing the prosecutors of misconduct are four former attorneys general, the Cabinet official appointed by the president to oversee all prosecutions by the U.S. Department of Justice: John Ashcroft, Ramsey Clark, Edwin Meese III and Michael Mukasey.

Other signers include former U.S. senator and Democratic vice presidential candidate Joe Lieberman, Republican mafia prosecutor and New York City mayor Rudy Giuliani, and Kenneth Starr, a former appeals court judge who led ethics investigations into President Bill Clinton in the '90s. Former Federal Bureau of Investigation directors Louis Freeh and William Sessions signed the letter as well.

It's a unique amount of support from political heavyweights that will grab the attention of U.S. Department of Justice officials tasked with deciding how to respond, said law professors contacted by The Des Moines Register whose names were not on the list.

But it's hardly the first time Rubashkin supporters and notable figures, including former judges and members of Congress, have publicly weighed in with concerns about how prosecutors and Reade handled the controversial case, said Laurie Levenson, a professor at Loyola Law School and former federal prosecutor familiar with the case. For instance, more than 80 former federal judges unsuccessfully asked the U.S. Supreme Court in 2012 to hear an appeal from Rubashkin, calling the sentence unjust.

Kevin Techau, U.S. Attorney for the Northern District of Iowa (Photo: United States Department of Justice)

Can renewed pressure convince Techau and others that the convicted executive was wronged and deserves a chance that could put him on a path toward freedom?

"There’s nothing to be lost by trying, but it hasn’t worked so far," Levenson said. "Unless they come up with new facts. That’s really the important thing. Not that you have big names, but that you have facts and law on your side.”

Federal prosecutors have until May 20 to file a response to the allegations by Rubashkin's attorneys. Assistant U.S. Attorney Steve Young said the office would not publicly discuss the claims outside of the filing.

Agriprocessors, owned by Rubashkin's father, Aaron, was the country's largest kosher meat company with more than $68 million in assets before U.S. Immigration and Customs Enforcement agents raided the plant on May 12, 2008. Nearly 400 Guatemalan and Mexican workers who were in the country illegally were arrested. The company filed for bankruptcy nearly six months after the raid on Nov. 4 and was eventually sold for $8.5 million to an investor who reopened the plant under the name Agri Star.

The March petition filed by Sholom Rubashkin's attorneys claim that it was improper interference by federal prosecutors in this bankruptcy sale, which was previously unknown, that led to the lengthy sentence.

Though the raid was focused on immigration offenses, it led to Rubashkin's 2009 trial and conviction on bank fraud and money laundering charges, with prosecutors arguing that the executive faked invoices and other sales records to make the company seem more financially healthy.

The falsified documents allowed the company to borrow more money on a $35 million line of credit from St. Louis-based First Bank Business Capital. Prosecutors argued that the fraud resulted in a $27 million loss for the bank that was unable to be recovered when Agriprocessors collapsed and was sold, a figure the judge relied on at sentencing.

However, the defense attorneys' petition claims there's new evidence federal prosecutors quietly used the bankruptcy sale to enforce a "no Rubashkins" rule in an attempt to ensure the family would not be involved with the company in the future.

An initial bid to buy Agriprocessors came in at $40 million, but the trustee overseeing the bankruptcy turned it away because the company was valued higher. However, several bidders have said in affidavits that they were spooked by prosecutors who warned that they could seize the company if a Rubashkin family member was found to be involved.

Key to the petition are recently uncovered notes from an attorney detailing a Dec. 5, 2008, meeting between federal prosecutors and the trustee overseeing the bankruptcy — who warned that threatening to seize the company could drive down the price in an auction, defense attorneys wrote.

At the meeting, Assistant U.S. Attorney Richard Murphy told the trustee and his attorneys, "No Rubashkins is very important to us — non-negotiable," according to the notes that were filed with the petition.

Paula Roby, an attorney who represented the trustee, later testified at the executive's sentencing hearing that the supposed "no-Rubashkin" policy was just a rumor among bidders. Roby testified, "The grapevine can be a very unreliable thing," despite having personally heard otherwise from prosecutors, the petition argues. Signers to the April letter said prosecutors knowingly committed an injustice by allowing the testimony to go unchecked.

The proper sentence under federal guidelines would have been approximately three years in prison if the amount of the loss was figured correctly, according to the letter, which was released to the Register by Rubashkin's defense team. Rubashkin, who is now 56, has already served almost seven years in prison, currently residing at a facility in New York.

"This conduct resulted in Mr. Rubashkin receiving an effective life-sentence for nonviolent offenses against a financial institution, despite considerable mitigating personal circumstances, including being a 51-year-old, first-time offender and father of 10," the letter to Techau reads. "… We respectfully submit that it is your duty to ensure that the miscarriage of justice that Mr. Rubashkin's extreme prison sentence represents is now remedied, not perpetuated."

In a separate letter to the chief prosecutor dated April 8, former U.S. Attorney for the Northern District of Iowa James Reynolds wrote that the actions by prosecutors were "insidious." The Rubashkin family's name was well-known and respected in the Orthodox Jewish and kosher foods communities, he wrote. Trying to entirely exclude the family from the business may have been illegal in the first place and certainly drove down the sale price, he wrote.

"Had this kind of unfair, underhanded and unnecessary misconduct occurred during my tenure, you can be absolutely certain that the perpetrators would have faced consequences, the very least of which would have been the loss of their job," wrote Reynolds, who left the office in 1982.

Guy Cook, a Des Moines attorney who represented Rubashkin in the fraud trial, said the amount of support the former executive is receiving is unlike anything he's seen in three decades practicing law. Mukasey, one of the former attorney generals who signed the letter, was leading the justice department in 2008 when Rubashkin was first arrested.

"This letter to the U.S. attorney is a remarkable assembly of governmental officials and other prominent persons calling for action," he said.

But Jeffrey Bellin, a professor at William and Mary Law School, said any defendant in Rubashkin's position faces an uphill battle to win a favorable outcome.

"No matter how well-known the signatories, I don’t think a letter directed to the United States attorney will by itself change any minds," he said. "The federal prosecutors handling the case likely understand the applicable law and the factual allegations as well as anyone."