I'd be willing to deal for some verifiable weapons info. Particularly if there's a weapons/money/france component. However, it wouldn't hurt to fire up the ole plastic shredder just to jog their memories a bit.
what they need to do is quickly try and hang one of them - I vote for Chemical Ali. Give him a 2 day trial, followed by a televised hanging (a slow one, none of this neck snapping stuff). Let the others see that on TV, and then see who comes forward.