Hah, he's necessarily dead, as this was more than a generation's lifetime ago.

As to hearsay, it is an unquestionable fact that Paul, as the direct founder of the Gentile branch of the Church (the only one existing now), existed, and a great deal about his life is known. In particular, it is known that he persecuted Christians and participated in one of the earliest executions of them (that of Saint Stephen) and that he was friends with and later had tensions with Peter (who was among the many people he had contact with who saw risen Jesus, which is simply what set everything in motion in the first place).

Besides, the well-known standard opinion around about this whole ordeal was simply that the disciples stole the body. But they, and only they, knew that they didn't.