I do not get how a big state will rely on such childish proofs.Seriously,a professional army who have history of fighting proxy war for a decade against a super power of past will plan their offense in such layman's way.Like they will give them Made in Pakistan food,medicines and Weaponry and make sure all the proofs track back to Pakistan,when made in every country's stuff is available in black Market at least.
Mumbai Attack's story is described in detail in Saleem Shehzad's book,like how Al qaeda planned the attack to engage Pak-India in a full scale war,divert Pakistan's attention from Pak-Afghan border,freely operate in Afghanistan from there,economically dent Pakistan and take full advantage of it.The same way they engaged USA in Afghanistan in a prolong war.
India should stop this policy of blaming every thing on Pakistan.It won't do them any good.Rather will give 3rd party time and space to take advantage of India's scattered investigation.