Just to share, I heard this version from a Muslim Scholar during Uni days.
Judas Iscariot accompanied the Romans soldiers to Jesus, but Jesus knew about the plot and fled the city. So, in order not to do nothing, the soldiers picked somebody standing around and said he was Jesus, and crucified that bugger anyways, And they shut the body in a cave after that. Three days later, the real Jesus came out of hiding and claimed he has resurrected; thereby fulfilling the scriptures! Not a bad scheme eh? May not be the officical story, but more possible than it.
Cheers!