The first so-called high-value prisoner held at the United States' Guantanamo Bay detention centre has pleaded guilty to murder, attempted murder and conspiring with al-Qaeda to commit acts of terror.
Majid Khan, a 32-year-old Pakistani, has been in secret US custody since 2003.
The BBC reports that a plea bargain document released by the US government says his sentence will be capped at 25 years in exchange for pleading guilty.
It is also expected he will testify against other detainees.
Khan is the seventh prisoner convicted by a military tribunal since the Guantanamo facility opened in January 2002 and the first high-profile detainee to be convicted.
The US military currently holds 171 prisoners at the prison.