The terrorist who killed two people and wounded several others in an attack Friday on the London Bridge sought deradicalization help during a previous prison sentence.

Usman Khan, 28, was previously convicted of conspiring to blow up several London landmarks, including the stock exchange, Westminster Abbey, and the American embassy. From prison in 2012, Khan wrote a letter requesting help from someone who could assist in deradicalizing him from the extreme ideology of Islamic State jihadists. “I would like to do such a course so I can prove to the authorities, my family and soicity [sic] in general that I don’t carry the views I had before my arrest, and also I can prove that at the time I was immature,” he wrote at the time. “And now I am much more mature and want to live my life as a good Muslim and also a good citizen of Britain.”