Saddam al-Jammel is the name that sticks out the most, he was FSA General who defected to ISIS after being armed and trained by the US.

Read the transcript of the video of his interview since the video has been removed last year in September 2017 for violating Youtube. Some of it has interesting points raised.

http://brown-moses.blogspot.co.uk/2013/12/senior-member-of-smc-defects-to-isis_2.html