NEW YORK (AP) -- A judge warned Osama bin Laden's son-in-law Wednesday that a lawyer he hired to represent him on charges he conspired to kill Americans could end up in prison himself.

U.S. District Judge Lewis A. Kaplan told Sulaiman Abu Ghaith that he could cause himself problems by choosing attorney Stanley Cohen to defend him against charges that he conspired against Americans in his role as al-Qaida's chief spokesman.

Cohen was indicted last year in Syracuse, N.Y., on federal charges that he failed to file individual and corporate tax returns between 2005 and 2010 and committed other tax-related violations. A federal prosecutor in Manhattan told Kaplan that additional charges may be filed against Cohen.

Kaplan asked Abu Ghaith a series of questions designed to make sure the 47-year-old defendant understood the hazards of rejecting three public defenders to have Cohen and another attorney represent him.

The judge said he wanted to make clear to Abu Ghaith that Cohen "has interests that are potentially in conflict with your own."

He also told him it was "quite possibly ill advised" for a defendant to proceed with an attorney who faces criminal charges himself, and he noted that Cohen might not be able to obtain security clearance from the government to view classified materials necessary to prepare for trial.

Abu Ghaith insisted he wanted Cohen to represent him after his brother in Kuwait hired the veteran civil rights attorney.

"I understood he's very enthusiastic about this case," Abu Ghaith told Kaplan. "I thank you very much but I've made my decision."

The judge set a hearing for next week to further explore the legal issue. He told the government to submit legal papers explaining its position on whether Abu Ghaith can be represented by Cohen and whether his understanding of his rights was sufficient to switch lawyers.

Abu Ghaith has pleaded not guilty to charges that he urged the death of Americans after the Sept. 11 terrorist attacks.

Prosecutors say evidence against Abu Ghaith includes a widely circulated video of him in early October 2001 sitting with bin Laden and current al-Qaida leader Ayman al-Zawahri and another in which he calls on every Muslim to join the fight against the United States, declaring that "jihad is a duty."

Cohen said outside court that he believes he was chosen because of his extensive contacts throughout the Middle East and his ability to travel and speak with witnesses where other lawyers cannot.

"I've probably done more terrorism cases - real and fake - than any other lawyer in the United States," he said.