ISB ~ Acts 4 v6

Annas the high priest:He served in this capacity from A.D. 6 to 15, at which time Roman authorities replaced him with another (Eleazar). The Jewish leadership, however, still considered him the rightful occupant of the position and so addressed him accordingly (Lk 3:2).

Caiaphas:The son-in-law of Annas and the officiating high priest appointed by the Romans in A.D. 18 (Jn 18:13).

John:Probably the son of Annas and the direct successor of Caiaphas. He was appointed high priest in A.D. 36.