A.T. Robertson Commentary John 20:14

"When she had thus said, she turned herself back, and beholdeth Jesus standing, and knew not that it was Jesus." — John 20:14 (ASV)

She turned herself back (εστραφη εις τα οπισω). Second aorist passive indicative of στρεφω in an intransitive and almost reflective sense. In the disappearance of the aorist middle before the aorist passive see Robertson, Grammar, p.817. See also στραφεισα (second aorist passive participle) in verse 16. On εις τα οπισω see 6:66; 18:6.

Standing (εστωτα). Second perfect active (intransitive) of ιστημ. Instinctively Mary felt the presence of some one behind her.

Was (εστιν). Present active indicative retained in indirect discourse after ηιδε (knew).