A federal prosecutor who has led a series of investigations into Islamic militants and Muslim groups based in Virginia, Gordon Kromberg, may soon be facing a trial of sorts himself, if defense lawyers get their way.

Attorneys for a former Florida college professor who pleaded guilty two years ago to aiding Palestinian Islamic Jihad, Sami Al-Arian, are asking a federal judge to hold a hearing on whether anti-Muslim bias led to the government’s decision to obtain a new indictment of Al-Arian in June for contempt for refusing to testify before grand juries pursuing the Virginia organizations.

While the motion claims Muslim terrorism suspects are generally treated unfairly by the Justice Department, Al-Arian’s lawyers argue that Mr. Kromberg, 51, has a particularly egregious record of intemperate statements and actions in a series of terrorism-related cases and investigations.

“Defense attorneys have objected for years that Mr. Kromberg, the lead counsel in many of these cases, has been using the Eastern District of Virginia to mete out his own brand of justice for Muslim terrorism subjects, often openly displaying his personal animus,” Al-Arian’s lead counsel, Jonathan Turley, wrote. “This long and controversial record forms the backdrop for the allegation of selective and malicious prosecution in this case.”

Al-Arian’s lawyers claim that in 2006, when Mr. Kromberg moved to obtain new testimony from the former professor following his guilty plea in Florida, the prosecutor “became agitated” in response to a defense lawyer’s request that the testimony be put off until after the Muslim holy month of Ramadan. “They can kill each other during Ramadan. They can appear before the grand jury; all they can’t do is eat before sunset,” Mr. Kromberg responded, according to a declaration written by one of Al-Arian’s attorneys, Jack Fernandez. Mr. Fernandez said the prosecutor described the request for a postponement as “all part of the attempted Islamization of the American justice system.” Mr. Fernandez wrote that he viewed the comments as exhibiting “apparent bias against Muslims.”

Mr. Fernandez also said Mr. Kromberg called the 57-month prison sentence Al-Arian received “a bonanza” for the Palestinian Arab activist. He had faced the potential of life in prison for acting as the leader of Palestinian Islamic Jihad in America, but a trial in 2005 resulted in his acquittal on eight counts and a mistrial on nine others where jurors could not reach a verdict. Al-Arian’s lawyers contend that the dogged pursuit of their client is retribution for the outcome of the Tampa trial, which was widely seen as a failure for the government.

The new motion also asserts that Mr. Kromberg joked about the torture of a Virginia man then being held in Saudi Arabia, Ahmed Abu Ali. The suspect’s lawyer, Salim Ali, said that when he asked Mr. Kromberg about the possibility of returning the young man to America, the prosecutor “smirked and stated that ‘he’s no good for us here, he has no fingernails left.'”

In a court declaration, Mr. Kromberg said that he had no recollection of making the statement and that he was arguing an appeal in another city when the comment was allegedly made.

Al-Arian’s lawyers are also pointing to the arguments Mr. Kromberg made in the trial of a Virginia cancer researcher and Muslim preacher, Ali al-Timimi, who was accused of exhorting others to wage war against America by joining the Taliban. In the case, Mr. Kromberg argued that the religious beliefs of the defendant and other witnesses made it acceptable to lie to kaffirs, or nonbelievers in Islam. “If you are a kaffir, Timimi believes in time of war, he’s supposed to lie to you,” the prosecutor told jurors. Al-Timimi was convicted of treason and sentenced to life in prison.

“Kromberg argued to the jury that Timimi and the other Muslim witnesses — their testimony should be disregarded just on the basis of their religion,” al-Timimi’s defense lawyer, Edward MacMahon Jr., said. “I think it’s an outrageous thing to argue in the courtroom. Imagine that directed at any other religion.”

Mr. Kromberg declined to be interviewed for this article and said a written response to Al-Arian’s motion would be filed in due course. In response to questions from The New York Sun, the U.S. Attorney for the Eastern District of Virginia, Charles “Chuck” Rosenberg, issued a written statement denying any bias and standing behind Mr. Kromberg’s work.

“Gordon Kromberg is a dedicated, talented, and scrupulously fair prosecutor,” Mr. Rosenberg said. “Further, when we decide to prosecute an individual, that decision is based strictly on the facts and the law, and in the pursuit of justice, period.”

A lawyer and former federal prosecutor who has squared off with Mr. Kromberg in court, Henry FitzGerald, said the prosecutor has acquired a reputation for leaving no stone unturned in cases relating to terrorism or funding for Islamic militant groups.

“Kromberg is absolutely relentless in his pursuit of everything that could be pursued in the way of forfeiture or prosecutions in this area. He’s just indefatigable, relentless, tireless,” Mr. FitzGerald said. “If you say he’s doing the country’s work to fight terrorism, that’s good, he’s a good fighter, but a lot of people say it’s overkill, he doesn’t listen to reasonable arguments. Everything is black until somebody takes him to court to prove it’s white.”

Mr. FitzGerald said Mr. Kromberg, while unusually persistent, does not take quixotic stances. “Kromberg’s not a dumb man. He’s smart. He’s not going to go out and take an utterly groundless case, raise hell with it, and get himself in trouble. He just goes straight ahead, doesn’t look left or right and pushes to the absolute limit,” Mr. FitzGerald said.

Mr. Kromberg sought Al-Arian’s testimony as part of an investigation into the finances of a Herndon, Va.- based think tank, the International Institute of Islamic Thought. In 2002, federal authorities executed search warrants at IIIT’s headquarters and more than a dozen other locations, including residences of the organization’s officers. Court papers said prosecutors had evidence of financial transfers involving the think tank, nonprofit groups, including some run by Al-Arian, and terrorist movements abroad, such as Palestinian Islamic Jihad.

A lawyer for IIIT, Nancy Luque, did not respond to repeated requests for an interview for this article. However, in 2006, she complained to the Washington Post that prosecutors had nothing to show for their raids. “You storm into people’s homes, take their children’s toys, terrorize the women, and 4 1/2 years later, you haven’t got a scintilla of evidence against them,” she told the Post.

A former federal terrorism prosecutor, Andrew McCarthy, said complaints that the Virginia probe is moving too slowly are silly coming from Al-Arian and others who have refused to cooperate. Several witnesses affiliated with IIIT have filed legal challenges to grand jury subpoenas and have pursued appeals to the 4th Circuit, resulting in lengthy delays. “I’m always amused when people who have obstructed an investigation for years, at the conclusion of years say, ‘Years have gone by and nothing has been revealed,'” Mr. McCarthy said.

Justice Department officials also reject the notion that the IIIT probe, which grew out of an effort dubbed Operation Green Quest, has yielded nothing. They note the arrest and subsequent guilty plea of Abdurahman Alamoudi, a former Muslim-American political leader and founder of the American Muslim Council, who admitted in 2004 to involvement in a Libyan plot to assassinate Crown Prince Abdullah of Saudi Arabia. Alamoudi, whose home was among those searched in 2002 and who worked for a group related to IIIT, the Saar Foundation, was sentenced to 23 years in prison. In addition, a financier with ties to Saar who left America just after the 2002 raids, Soliman Biheiri, got 13 months in prison for immigration fraud and lying to customs agents.

Still, it is true that the principals in IIIT and the organization itself have not been charged, more than six and a half years after the investigation began.

Mr. McCarthy said Mr. Kromberg’s statements about Islam seemed directed not to ordinary followers but to the beliefs of certain radical Islamic extremists. “If he’s got an innate feeling of disapproval and hostility to that, I don’t see the slightest problem with that. I do too, and so do most Americans,” the ex-prosecutor said. “If he’s concerned about the Islamization of our legal process or the idea that we should be recognizing certain tenets of Islamic law as we conduct law enforcement… Gordon is not the only prosecutor ever to have taken that position.”

Al-Arian’s motion includes no claim that Mr. Kromberg’s alleged anti-Muslim animus is related to him being Jewish or to a pro-Israel bias. However, the Atlantic magazine and a left-leaning news agency, Inter Press Service, have called attention to a travelogue Mr. Kromberg wrote after traveling on a United Jewish Communities mission to Israel in 2002.

In the diary, Mr. Kromberg complained that Israel is losing the global public relations battle because of “a lack of resources on the Israeli side to provide information to the innumerable members of the press who are fed lies by the Palestinians (‘hundreds were massacred in Jenin’).”

“Bibi Netanyahu can only be in so many places at one time to answer so many questions,” the prosecutor lamented.

Mr. Kromberg’s journal also refers to the West Bank as “Judea and Samaria,” which Inter Press described as “a term favored by right-wing Israelis.”

As a whole, the diary exhibits a hostility toward Palestinian terrorism and a strong affinity for Israel, but gives no indication Mr. Kromberg is particularly religious. He wrote that he does not speak Hebrew and that his tour group opted to go shopping rather than visit Jerusalem’s Western Wall.

Many Muslim activists consider Mr. Kromberg to be a doppelganger of a journalist and author of books warning about the threat posed by Muslim radicals in America, Steven Emerson. The selective prosecution motion asks for a hearing to explore why the prosecutor’s statements “appear to track writings” by Mr. Emerson.

In an interview with the Sun, Mr. Emerson called the motion’s claims about him and Mr. Kromberg “baseless.”

Mr. Kromberg grew up in the village of Lawrence in Nassau County, just east of Queens. He volunteered briefly at an Israeli kibbutz and went to college at Princeton University, where he took part in the Reserve Officer Training Corps. The future prosecutor attended New York University Law School, where he graduated in 1982.

In the 1980s, Mr. Kromberg spent several years in South Korea as a military defense attorney in the Army’s Judge Advocate General Corps, before taking a job in the Justice Department’s civil division in 1987. He is still in the Army Reserve, where he holds the rank of Lieutenant Colonel.

In 2000, Mr. Kromberg briefly joined the staff of the independent counsel investigating President Clinton, Robert Ray. At the time, the impeachment trial was long over and Mr. Ray was considering whether to bring criminal charges against Mr. Clinton. They were never filed.

That year, Mr. Kromberg started work at the U.S. Attorney’s Office in Northern Virginia, where he became a specialist in seizing money, cars, boats, and houses allegedly used in drug dealing and other crimes. Defense lawyers, civil libertarians, and some conservatives criticized the tactic as an end run around the government’s obligation to prove criminals guilty beyond a reasonable doubt. As that criticism mounted, Mr. Kromberg became a point person in the Justice Department’s effort to fend off legislation which would have made it tougher for the government to confiscate such property.

Some of the ire directed at Mr. Kromberg by the Muslim community stems from his vigorous prosecution of the so-called Paintball Eleven, a group of Muslims accused of training in Virginia to fight with a Pakistani militant group, Lashkar e-Taiba, against Indian forces in Kashmir. Nine of the eleven men were convicted at trial or pled guilty. Two were acquitted.

Mr. Kromberg later called one of the acquitted men, Sabri Benkahla, before grand juries and questioned him about his attendance and activities at jihad training camps in Afghanistan or Pakistan. Convinced that Benkahla’s answers were false, the prosecutor obtained an indictment of Benkahla for obstruction of justice and making false statements to the FBI and the grand juries.

As with Al-Arian, defense lawyers for Benkahla said the perjury charges amounted to an effort by Mr. Kromberg to retry the earlier case in which Benkahla was acquitted.

“When you look at the prosecutions together, there is a pattern that really doesn’t make Mr. Kromberg look very good,” a Muslim scholar from Maryland who has been subpoenaed in the IIIT probe, Imad-ad-Dean Ahmad, said. “It reminds me of the Red Scare. Communism was a serious problem for America, but some people seemed to think almost every liberal was a Communist. Mr. Kromberg and a handful of other people in the government seem to have the same approach when it comes to outspoken Muslims.”

Mr. Ahmad said the punishments for those convicted in the Paintball or, as the government prefers, Virginia Jihad, cases, were too extreme for individuals who planned no act of violence in America. “It’s hard to imagine there isn’t someone in the Department of Justice saying, ‘Why are we doing this?'” he said.

Even Mr. Kromberg’s critics acknowledge that he has a strong record of prevailing in court. Last month, a three-judge panel of the 4th Circuit unanimously upheld Benkahla’s convictions and rejected the arguments that he was unconstitutionally put on trial twice for the same crime. “The investigations in which Benkahla was interviewed and the questions he was asked show no sign of having been manufactured for the sake of a second prosecution,” Judge James Wilkinson III wrote. The court also upheld a 10-year prison sentence for Benkahla.

However, there are new signs that some judges have begun to chafe at Mr. Kromberg’s aggressiveness.

Late last year, Judge Gerald Lee, who ordered Al-Arian jailed for a year on civil contempt, raised questions about the strategy pursued against the former professor. “Judge Lee expressed his frustration with the government’s continued attempt to use contempt measures against Dr. Al-Arian and stated that he did not view these proceedings as a good use of the time and resources of either the government or the Court,” Mr. Turley wrote to Mr. Kromberg, describing a court hearing in December. The e-mail was attached to a defense pleading filed recently in the criminal case. The defense attorney also wrote that the judge had urged Mr. Kromberg to ask Attorney General Mukasey, who had just been sworn in, for a “new review of the case.”

Precisely what Judge Lee, Mr. Kromberg, or Mr. Turley said at the hearing is not publicly known because the judge refused this reporter’s request for public access to the proceedings. A legal challenge to the secrecy is pending before the 4th Circuit.

At a bail hearing for Al-Arian earlier this month, Judge Leonie Brinkema sounded skeptical about the new contempt charges against him. “There’s some strange signals coming out of this case,” she said, according to the Associated Press. “I expect the Department of Justice to live up to its agreements.” She granted bail to Al-Arian, but he remains in jail on orders from immigration authorities.

Still, Al-Arian may not get far with his argument that Mr. Kromberg used religion to win a tainted conviction against al-Timimi. Judge Brinkema, who will have to rule on the selective prosecution motion, presided over al-Timimi’s trial and rejected defense motions that Mr. Kromberg’s comments improperly invoked the defendant’s religion.

The frustration and anger Mr. Kromberg provokes in some quarters may stem from an irreverence he sometimes displays in his dealings with defense attorneys and the courts.

In his declaration about Abu Ali, the terrorism suspect who claimed torture in Saudi Arabia, the prosecutor deadpanned, “I do not have any other information that would lead me to believe that he has anything wrong with his fingernails.”

When Mr. Turley told Mr. Kromberg that “many” viewed the effort to force Al-Arian before a grand jury as a “transparent perjury trap,” the prosecutor shot back an e-mail pointing out that a federal judge in Tampa found that Al-Arian lied to his neighbors for years by denying involvement with Palestinian Islamic Jihad. To underscore his point, Mr. Kromberg invoked a legendary British rock band.

“I hope that the next time that your client tries to convince the ‘many’ to whom you refer that he is something that he is not, that ‘many’ will remember the slogan of the Who, and loudly sing out together, ‘We won’t get fooled [by your client] again!'” the prosecutor wrote.