HATTIESBURG — The only company executive indicted in the nation's largest workplace raid on illegal immigrants pleaded guilty Wednesday to one count of conspiracy.

Jose Humberto Gonzalez pleaded guilty to one charge of a 12-count indictment that alleged he knowingly hired illegal immigrants at Howard Industries, where he was personnel director.

Prosecutors would not discuss details of the plea agreement.

More than 600 were arrested in the August 2008 raid on Howard's plant in the south Mississippi town of Laurel. Gonzalez, 45, was the human resources manager at the sprawling facility, which makes electrical transformers.

Several illegal immigrants have been convicted of identity theft and deported.

Gonzalez, wearing a dark brown suit, said little during the hearing other than responding to the judge with yes or no answers.

The court docket was backed up, so U.S. District Judge Keith Starrett conducted plea changes for two other men in unrelated cases at the same time as Gonzalez. That left Gonzalez standing before the judge next to a shackled crack dealer in a red prison jumpsuit.

Gonzalez refused to comment as he left the federal courthouse holding hands with his wife.

Gonzalez attorney, P.K. Holmes of Arkansas, passed out a written statement saying Gonzalez is prohibited from commenting on specifics of the case even though he wants to and "accepts responsibility for his actions."

He faces up to five years on the conspiracy charge. Sentencing is March 31.

As part of his plea, Gonzalez admitted to elements of the conspiracy, including hiring workers "regardless of concerns about their lawful status."

In December 2005, many workers fled the plant as rumors spread of a coming raid. Gonzalez "was summoned to the plant" to call workers and reassure them there was no raid and to tell them to come back to work, Assistant U.S. Attorney Gaines Cleveland told the court.

"Gonzalez also visited the plant floor in the company of senior Howard Industries personnel to reassure foreign workers not to be concerned about the immigration raid rumor," Cleveland said.

Still, defense attorney Frank Trapp told The Associated Press outside of the court that no other Howard executives knew the company employed illegal immigrants.

Howard Industries is one of the most successful private companies in Mississippi.

In a statement Wednesday, the company said Gonzalez was placed on leave after his indictment in May and resigned Wednesday, the same day he pleaded guilty.

"The company was surprised and saddened by these announcements," said Denise Wade, an assistant to company president Michael Howard. "As previously announced, the company has cooperated at all times with the government's investigation and the government has not accused Howard Industries of any wrongdoing."

The company said it had always had "a strict policy to hire only U.S. citizens or those who have legal authorization to work in the United States" and has since implemented even more safeguards, including a fingerprint identification system for its employees.

The indictment in the case had also accused Gonzalez of instructing some workers to obtain fake documents and hiring one man who had previously worked at the plant under a different name. It also accused him of hiring people after the Social Security Administration told him their identities were not valid.

Most of the workers detained in the raid were deported in the following months.