Yes, you look alike, and the body of one guy mysterious disappeared, therefore, you are that same guy, and must therefore be either immortal and/or undead. There's some flawless logic...
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)