I doubt it. John’s killer came from Hawaii to murder him...he could just as easily have found him in England. I am honestly surprised that Chapman survived in prison, given the popularity of who he slaughtered. Poor John.
Sure, he could have found him in England. But, it would have been another step in the way. Dunno, how easy it would have been for him to find a gun in England. He could have used any other tool. John should have been deported long ago.