WASHINGTON (AP) - Republican and Democratic lawmakers alike are demanding to know why the Bush administration chose to release to Syria a terror suspect when several prosecutors and FBI agents had collected evidence for a possible criminal case.

The circumstances surrounding Nabil al-Marabh's release, detailed in a recent Associated Press story, are "of deep concern and appear to be a departure from an aggressive, proactive approach to the war on terrorism," Senate Finance Committee Chairman Charles Grassley, R-Iowa, wrote Tuesday in a letter to Attorney General John Ashcroft.

The Iowa Republican repeatedly cited the AP story and demanded that Ashcroft answer 19 questions about al-Marabh's case, including why the Justice Department didn't prosecute the man they had in custody for nearly two years either in a military tribunal or through a secret court proceeding that could protect intelligence information.

Grassley also asked Justice to detail what has happened to other terror suspects that appeared on the same post-Sept. 11 terrorism list as al-Marabh.

Aides to Senate Judiciary Committee chairman Orrin Hatch, R-Utah, have also made some preliminary inquiries into the case.

One of Ashcroft's top deputies, Chris Wray, recently told Congress that he was concerned some terror suspects rounded up after Sept. 11, 2001, were now being deported because prosecutors were having a hard time making terrorism cases or couldn't expose sensitive intelligence information during court proceedings.

Justice officials told AP that despite concerns about al-Marabh's possible ties to terrorism, deportation was "determined to be the best option available under the law to protect our national security," including intelligence sources and methods.

Separately, Sen. Patrick Leahy, the top Democrat on the Judiciary Committee, also has asked Ashcroft to answer questions about issues raised in the AP story but has yet to receive answers.

"Why was a suspected terrorist returned to a country that sponsors terrorism? We need to know that the safety of the American people and our strategic goals in countering terrorism are paramount factors when decisions like this are made," Leahy, of Vermont, said Tuesday.

Sen. Charles Schumer, D-N.Y., another Judiciary Committee member, said Tuesday the Justice Department's explanation that al-Marabh's deportation was the best option does not make sense. "It seems that pursuing a military tribunal, a classified criminal trial or continued immigration proceedings would have made more sense than merely deporting a suspected terrorist."

AP reported June 2 that the Bush administration earlier this year set al-Marabh free to Syria, a country regarded as a state sponsor of terrorism, even though prosecutors in several cities sought to bring criminal cases against him and judges openly expressed concerns about al-Marabh's possible terrorist ties.