Just realized John the baptist spoke prophetically concerning Jesus in John 1:29
"The next day John seeth Jesus coming unto him, and saith, Behold the Lamb of God, which taketh away the sin of the world."
Then later, while he was in prison, he sent messengers Matthew 11:3
"And said unto him, Art thou he that should come, or do we look for another?
Jesus' answered Matthew 11:4-6
"Jesus answered and said unto them, Go and shew John again those things which ye do hear and see: The blind receive their sight, and the lame walk, the lepers are cleansed, and the deaf hear, the dead are raised up, and the poor have the gospel preached to them. And blessed is he, whosoever shall not be offended in me."
John the baptist doubted, and Jesus didn't answer yes I am he. He showed many witnesses to his ministry, as the miracles themselves were foretold in Isaiah 61:1.