[JURIST] Saudi Guantanamo Bay [JURIST backgrounder] prisoner Ahmed Muhammed Haza al Darbi [JURIST news archive] on Thursday pleaded guilty [pretrial agreement, PDF] to involvement in terrorism-related activities, including the 2002 al Qaeda plot to blow up oil tankers near Yemen. Had al Darbi gone to trial, he faced a potential sentence of life imprisonment. However, the plea agreement stipulates that he is to serve no more than 15 more years behind bars, in addition to the 12 years he has already served. Al Darbi will continue to be detained at Guantanamo until he is officially sentenced. After that point, he will likely be transferred to serve the rest of his sentence at a prison in Saudi Arabia. As part of his cooperation with prosecutors, al Darbi is expected to testify in the upcoming case against fellow Saudi detainee Abd al-Rahim al-Nashiri [JURIST news archive].

This is the latest in al Darbi’s legal proceedings. In 2012, the detainee was accused of numerous terrorism charges [JURIST report], including conspiracy, aiding and abetting attacks on civilians, and aiding and abetting terrorism based on his former work as a weapons instructor, contact with Osama bin Laden and support of bombing civilian oil tankers. Al Darbi dodged similar charges in 2009 when the Obama administration contemplated closing Guantanamo Bay. Those proceedings were delayed several times before being dismissed, but not before al Darbi announced his plan to boycott [JURIST reports] the military commission as a “sham” and a “crime against humanity.” The original two charges were filed in 2008 [JURIST report] after it was alleged that al Darbi had formerly conspired in support of terrorism. Al Darbi received his first infamous attention in 2007 when the Department of Defense revealed that he is the brother-in-law [JURIST report] of Khalid al Mihdar, a 9/11 hijacker. Al Darbi was captured in Azerbaijan in 2002.