A.T. Robertson Commentary John 18:5

"They answered him, Jesus of Nazareth. Jesus saith unto them, I am [he]. And Judas also, who betrayed him, was standing with them." — John 18:5 (ASV)

Was standing (ιστηκε). Second past perfect active of ιστημ used as imperfect, a vivid picture of Judas in the very act of betraying Jesus. John does not mention the kiss by Judas as a sign to the soldiers and police. Tatian suggests that it came before verse 4. Then Jesus stepped forth and affirmed that he was the one whom they were seeking.