The "captain of the Temple" in Acts 4:1 was probably the commander of the Temple guard on duty at the time.

When the priests and Sadducees heard John and Peter preaching at the Temple, they all came running. Corrupt authorities can't tolerate competition. The Sadducees had two complaints against Peter and John in Acts 4:2:
1) They didn't have approved credentials, which was offensive to the Pharisees.
2) They were teaching resurrection, which was contrary to a core doctrine of the Sadducees.

If Yeshua had really risen, the news would destroy the authority of the Sadducees. I'm not sure they even cared if it was true or not. The threat of The Way to the power base of the Sadducees and Pharisees was so obvious that the Sanhedrin was convened together with the chief priests to discuss it and to question Peter and John.
Acts 4:1-2