When the Bush Administration rolled out charges against five Gitmo detainees last week for their alleged roles in the 9/11 attacks, there were a lot of questions about why the suspected 20th hijacker was not charged.

The Wall Street Journal today suggests one answer:

An alleged 20th hijacker in the Sept. 11 conspiracy attempted suicide rather than face a Guantanamo Bay military commission and now suffers from such mental impairment that he can't adequately help in his own defense, his civilian lawyer says.

The contention suggests one possible reason the Defense Department last week dismissed charges against Mohammed al-Qahtani, who faced a potential death penalty if convicted in the Sept. 11, 2001, terrorist attacks. At the time, the administrator of the military commissions, Susan Crawford, gave no explanation. Mr. Qahtani remains under indefinite detention, and prosecutors may seek to file amended charges.

In 2002 Mr. Qahtani suffered a severe and prolonged interrogation that a Pentagon review later labeled "abusive and degrading." Some military investigators and prosecutors feared that the coercive treatment had ruined a potential case against Mr. Qahtani, under legal and ethical rules.

Intriguingly, we may yet learn more about al-Qahtani's interrogation, the Journal reports:

Friday, a military judge ordered such an inquiry for Guantanamo defendant Salim Hamdan, Osama bin Laden's former driver, after a psychiatrist hired by the defense reported that Mr. Hamdan was suffering from "major depression" and expressed suicidal thoughts.

If a military judge were to order a similar examination for Mr. Qahtani, it could force the first independent inquiry into his interrogation, which to date has been reviewed by only the Pentagon.

The prospect of two key Guantanamo defendants being incapable of standing trial is another problem for a military commissions system already beset by legal challenges and staff unrest.

Late Update: Speaking today about al-Qahtani's suicide attempt, his lawyer told AP that she didn't learn of his suicide attempts until weeks after it occurred:

Gutierrez said the military did not inform her or al-Qahtani's family of the alleged suicide attempt. She said she learned of it when she went to visit him and noticed three scars on his hand, inside wrist and inner forearm near the elbow.

The prisoner seemed desolate during the meeting, said the attorney, who has met with him more than 20 times.

"This was the worst I have ever seen him in terms of his psychological state," she told The Associated Press. "He just can't take it anymore and just kept threatening to kill himself."