A.T. Robertson Commentary Mark 14:69

"And the maid saw him, and began again to say to them that stood by, This is [one] of them." — Mark 14:69 (ASV)

To them that stood by (τοις παρεστωσιν). This talk about Peter was overheard by him. "This fellow (ουτος) is one of them." So in verse 70 the talk is directly to Peter as in Mt 26:73, but in Lu 22:59 it is about him. Soon the bystanders (ο παρεστωτες) will join in the accusation to Peter (verse 70; Matthew 26:73), with the specially pungent question in Joh 18:26 which was the climax. See on Mt 26:69-75 for discussion of similar details.