Who had arrested Jesus
The high priest.
And the elders
Οἱ δὲ κρατήσαντες τὸν Ἰησοῦν ἀπήγαγον πρὸς Καϊάφαν τὸν ἀρχιερέα, ὅπου οἱ γραμματεῖς καὶ οἱ πρεσβύτεροι συνήχθησα
This is similar to Mark, chapter 14:53, but Caiaphas was not mentioned there. In Luke, chapter 22:54, Jesus was simply brought to the high priest’s house, while in John, chapter 18:13-14, they brought Jesus to the house of the father-in-law of Caiaphas, Annas, who had been a high priest. from 6-15 CE, before he was removed by the Romans at the age of 36, even though he lived to the age of 61. Thus, he had a lot of influence on things. John remarked that Caiaphas had said it was better for one person to die for the people. Caiaphas was the high priest from 18-36 CE since he had married the daughter of Annas. Matthew said that those who had seized, arrested, or captured Jesus (Οἱ δὲ κρατήσαντες τὸν Ἰησοῦν) took him to the house of Caiaphas, the high priest (ἀπήγαγον πρὸς Καϊάφαν τὸν ἀρχιερέα). Apparently, the Scribes and the elder presbyters had gathered or assembled there (ὅπου οἱ γραμματεῖς καὶ οἱ πρεσβύτεροι συνήχθησα). Was this an official meeting of the Jerusalem Sanhedrin? Probably not, because these official meetings could not be held during the festival days or during the Passover. On the other hand, some kind of informal meeting was possible. However, there was no mention of the Pharisees and the Sadducees being there either.