Why is Adoboli alone facing the music?

Seeing Kweko Adoboli as the lonely accused in the Courtroom creates a certain amount of sympathy for the young man. It is easy for senior UBS staff to pin all blame for the billion dollar disaster on one person. This makes it easy to escape blame for a  management culture that allowed a completely insufficient risk control to exist. Senior managers were busy enough chasing profits at any price with a firm eye on the next bonus payment they expected to receive. But Risk Management should mean that fail-safe procedures are in place - if necessary in triplicate - that make it impossible for any single person to play the markets the way Adoboli is accused of having done. Senior managers have been fired (with or without a 'golden handshake' as farewell present?) but should there not be other people facing justice in the courtroom? Oswald Gruebel may have wished for a more glorious end to his career, but he will certainly not feel any pain in his pocket.