Long-Serving Prosecutor Quits Sept. 11 Case at Guantánamo Bay

One of the longest-serving prosecutors in the Sept. 11, 2001, case is stepping down, citing the pressure of his repeated trips to Guantánamo Bay on him and his family.

The prosecutor, Edward R. Ryan, is a Justice Department lawyer who served on a team of civilian and military prosecutors who for 15 years have sought to start the trial of Khalid Shaikh Mohammed and four other prisoners accused of conspiring in the hijackings that killed nearly 3,000 people in New York, in Pennsylvania and at the Pentagon.

Mr. Ryan’s decision was seen as a sign that the case would not be going to trial anytime soon.

He represented the government at the prisoners’ original court appearance at Guantánamo in 2008 and participated in nearly all the pretrial hearings since then.

On Wednesday, Mr. Ryan told family members of victims of the attacks by email that he was leaving “with the heaviest heart” to return to North Carolina. There he will resume work as a federal prosecutor, the job he had before his Guantánamo assignment.

“The challenges that come with the passage of time and trying to work so far from home have simply become too difficult for me and my extended family,” he said.

The case has been mired in pretrial hearings over what evidence would be admissible at the national security trial, which is expected to last more than a year when it eventually starts.