During the 26/11 Mumbai attack Ajmal Kasab was intercepted alive by the Mumbai police and the capture of a foreign terrorist led to an intricate legal battle as Mumbai police filed an 11,280 page chargesheet. The FBI filed four Chargesheets in the same case in a US court. The investigative mechanism adopted by the US and India for 26/11 attacks case inspire different degree of confidence. As for the terrorist crime, much is said for its prevention, and even the Afghan War against Taliban is said to be future security of the US and the world. But punishment without fail is very much important for prevention. The legal trial of the Mumbai case is different as legal structure of counts of indictment of such a crime which are thought to be applied in ordinary crime which occur in ordinary life, does not appropriately reflect actual social reality of the crime, of it's gravity, of it's structural whole, of each criminal's role. How far India’s and US’ investigation in the Mumbai attacks case establishes the design, plan and purpose of the crime? Is the post crime legal procedure of India and the US is deterrence for terror attack or otherwise? The article examines these questions both theoretically and empirically, with specific analysis of the chargesheet filed by the Mumbai police and FBI. Theoretically I identify various aspects – legal infrastructure, forensic data, electronic interception, intelligence input and conventional method of investigation – and hypothesized that there are different level of conviction for the same crime in both these countries.