President Trump issued his first prison commutation Wednesday to a man whose business was caught employing 389 illegal immigrants in a single shift, dismaying anti-illegal immigration advocates and a former prosecutor on the case.

With Trump's rare use of clemency, Sholom Rubashkin left prison seven years into a 27-year sentence.

"He was up to his hips in illegal immigration," said Robert Teig, a former assistant U.S. attorney involved in prosecuting Rubashkin. Before his conviction, Rubashkin oversaw operations at Agriprocessors, his father's company and once one of the nation's largest kosher meat producers.

A 2008 raid of the company's Iowa meatpacking facilities resulted in the mass arrest of workers, many of whom were convicted of using false documents and deported. Later, the business went bankrupt and prosecutors dropped immigration charges to focus on bank fraud and money laundering crimes.

"The government went in on just one of the shifts. There were two or three shifts," Teig said. "The rest of the illegal workforce didn't show up after that and that's what caused the business to fail. He built his business on the back of illegal immigrants."

ABC News reported that the bust was "the largest single raid of a workplace in U.S. history." But it’s too late for Rubashkin to face trial for immigration-related crimes due to a five-year statute of limitations, Teig said.

In announcing Trump's first prison commutation, the White House cited the support of members of Congress from both parties who lobbied for a commutation, including House Minority Leader Nancy Pelosi, D-Calif. Harvard law professor Alan Dershowitz personally asked Trump to give the commutation and a group of former U.S. attorneys general backed claims Rubashkin's was an unfairly harsh sentence.

Prosecutors said at sentencing that Rubashkin was found to have "cheated a bank and others out of a staggering amount of money — more than $26 million." His conviction on 86 federal counts was upheld on appeal.

“Clearly this is bad optics. This guy really is an exploiter of illegal immigrants, not to mention a criminal in a whole variety of respects,” said Mark Krikorian, executive director at the Center for Immigration Studies, which favors tighter immigration controls.

Krikorian said he hopes the Trump administration will offset clemency for Rubashkin “by arresting some more employers of illegal immigrants and trying them and actually locking them up," though he's not sure if it will happen.

Ira Mehlman, media director at the Federation for American Immigration Reform, which seeks to reduce immigration, also was disappointed.

"This guy was the poster boy for all of the abuses that have taken place because of our nation's failure to enforce immigration laws,” he said.

"There wasn't an ethical or moral code he didn’t violate,” Mehlman said. “You have to assume that the president of the United States, when he issues a commutation, has all of the facts in front of him, but you never know.”

White House spokespeople did not respond to requests for comment on whether Trump knew that Rubashkin was one of the country’s largest employers of illegal immigrants.

The Justice Department did not comment on whether the clemency was first vetted by the Office of the Pardon Attorney.

“I’ll bet you dollars to donuts that they didn’t ask the prosecutors,” Teig said. He said that Rubashkin’s supporters "from the outset waged a concerted campaign of dishonesty."

Teig said Rubashkin laundered money through charities for years and made unfounded claims of anti-Semitism against prosecutors. "Every judge who knew the facts rejected their claims, so obviously they had to take their campaign outside," he said.

The former prosecutor said he does not believe Rubashkin's claims to have been unaware of the legal status of workers, saying the company was notified that Social Security numbers of employees matched those of other people.

"People call them undocumented workers. They weren't undocumented, they had false documents ... He knew that the documents were false," Teig said.

An attorney who represented Rubashkin, Guy Cook, said Rubashkin wasn't as guilty as it may appear.

“Rubashkin had employment lawyers reviewing the veracity of employee documents prior to the raid,” Cook said. “Regardless, the government dismissed the immigration charges. The charges were just that, charges and proof of nothing.”

Cook said “Rubashkin was working to correct any issues” and that his attorney “asked for a meeting with ICE days before the raid to address the issues [and] ICE refused to respond and proceeded with the military-style raid.”

Cook said “the only immigration-related case that went to trial — alleged child labor violations — resulted in a total acquittal” in a state court trial. The defense argued Rubashkin didn't know some employees were children.

“President Trump is to be commended for listening to the remarkable bipartisan group of members of Congress and over a hundred former senior justice officials calling for Rubashkin’s release,” Cook added. “The 27-year sentence imposed for alleged bank fraud, in essence borrowing more money than his father’s company was allowed to borrow, was unfair, unjust, and essentially a life sentence.”

“President Trump did what is right and just. It had nothing to do with illegal immigration,” Cook said.

Trump, a forceful critic of illegal immigration, used his clemency powers only once before. In August, he pardoned immigration hardliner Joe Arpaio, a former Arizona sheriff convicted of contempt for defying a judge’s orders on immigration enforcement.

Trump did not respond to a twice-shouted question Thursday evening as he walked to the Oval Office regarding whether he knew Rubashkin employed hundreds of illegal immigrants.

Teig, the former prosecutor, said although he’s personally outraged, he doubts the matter will linger in public debate.

"It's one case of peddling influence, and in a week it will go away because the real facts will be ignored,” he said. "Factually, he had no way to get around what he earned with his sentence, so he had to go with influence, and it's sad to see that."