Based on information from intelligence agencies of Germany obtained from former members of the group, French authorities allege that Diab was a member of the Popular Front for the Liberation of Palestine, the group blamed for the bombing.[18] Evidence unsealed as part of the extradition case, in April 2009, included two police sketches made some time after the bombing. Samples of Diab's handwriting, while a student at Syracuse University years later, were subjected to handwriting analysis.