Evidence? We don't know whether BP was negligent because we haven't heard their account of the incident and because it hasn't yet been considered by the courts. The case against BP seems weak because the rig was owned and operated by Transocean, the blowout preventer was manufactured by Cameron International and Halliburton were responsible for cementing the well. If you let me know which if any of those you disagree with I'll try to point you to a relevant resource.