"training prop" to teach torture techniques to trainee CIA interrogators. One torture technique, known as "walling", was often practiced on Baluchi. In it, trainees would line up and take turns "shoving" a naked and tied-up Baluchi head-first into a plywood wall behind him, with sessions typically lasting for a few hours each. One of the instructors identified the goal being to "bounce" Baluchi's head off the wall. Analysis carried out by a neuropsychologist in 2018 found "abnormalities indicating moderate to severe brain damage" consistent with traumatic brain injury in Baluchi's brain. In addition, the inspector general said that interrogators in the black site also carried out torture that went beyond the CIA's guidelines, including dousing him with ice water and forcing him to kneel backwards with a stick behind his knees in a stress position. In a senate report from 2014, officials noted: "al-Baluchi was tortured and forcibly dunked into a tub filled with ice water. CIA interrogators forcibly kept his head under water while he struggled to breathe and beat him repeatedly with a truncheon-like object hitting him and smashing his head against a wall." In December 2005, Human Rights Watch listed him as a "ghost detainee" held in the CIA prison system. Baluchi was kept in CIA custody until 6 September 2006, when he was transferred to Guantanamo Bay Prison in Cuba. Other plots to attack civilian targets According to US investigators, Baluchi told them that al-Qaeda had set up a biological weapons lab and he asked Aafia Siddiqui (who has a biology degree from MIT) advice on how long it would take to develop such weapons and whether the man in charge was capable of developing the weapons. Siddiqui replied that she "was willing to participate in a biological weapons (BW) project if al-Qaida tasked her to do so". Another plot involving Baluchi alleged by US investigators involved Heathrow airport. According to Balochi's file, he told interrogators that he became aware of a plan to attack Heathrow airport in January 2003 and had intended to seek help from a more senior al-Qaida operative, Walid bin Attash, to carry it out. An "analyst note" in the files notes that the plot called for "crashing numerous airplanes into Heathrow, with a secondary explosion immediately outside of the airport as a diversion". It collapsed after KSM was arrested in March 2003. Guantanamo Bay On 6 September 2006, Baluchi was transferred