In an institution already cloaked in mystery, puzzling happenings seem to be afoot at Guantanamo Bay prison.

Not only have many legal files suddenly disappeared from the defense team's computers, but also hundreds of thousands their documents have landed on the prosecution's computers, according to Reuters. This debacle has caused several pretrial hearings in the prison's military tribunals to be delayed.

It's not clear how the files vanished or if there was any illegal action behind the disappearance. It could have been a simple computer blip, IT issues, a security breach, hackers, or one of the two sides instigating. So far, nothing seems to have been ruled out. CNET contacted the U.S. Department of Defense for more information and we'll update the story when we hear back.

In the incident involving the missing files, lawyers representing suspects housed in Guantanamo say that their confidential files have been disappearing from Pentagon computers since February, according to Reuters. They also say that they have evidence that third parties might have monitored their e-mails.

These lawyers are representing both Abd al Rahim al Nashiri, who is charged with leading the assault on the USS Cole off Yemen in 2000 that killed 17 U.S. sailors, and five prisoners who are charged with plotting the September 11 attack on the World Trade Center.

"Entire files, months of work was just gone," said Navy Cmdr. Stephen C. Reyes, an attorney for Nashiri, according to the Washington Post. "I have no evidence of any nefarious conduct, but it demonstrates again that we don't have confidence that our files and communications are secure."

In the other incident, about 540,000 defense e-mails landed on prosecutors' computers, according to the Washington Post. Within those e-mails were confidential attorney-client communications. It's unclear if these e-mails had anything to do with the missing files or involved the same cases.

This isn't the first time that classified Guantanamo files have been leaked. In 2011, WikiLeaks released nearly 800 secret dossiers from the U.S. prison in Cuba. In this data dump, sensitive information on Guantanamo detainees was released along with questionable activity carried out by the U.S. military.