A.T. Robertson Commentary Mark 14:61

"But he held his peace, and answered nothing. Again the high priest asked him, and saith unto him, Art thou the Christ, the Son of the Blessed?" — Mark 14:61 (ASV)

And answered nothing (κα ουκ απεκρινατο ουδεν). Mark adds the negative statement to the positive "kept silent" (εσιωπα), imperfect, also in Matthew. Mark does not give the solemn oath in Matthew under which Jesus had to answer. See on Matthew.