Verb epistamai (to know, to understand) in the Gospels-Acts

(Translation from NRSV)

Mark

14: 68But he denied it, saying, "I do not know or understand (epistamai) what you are talking about." And he went out into the forecourt. Then the cock crowed.

Acts

10: 28and he said to them, "You yourselves know (epistamai) that it is unlawful for a Jew to associate with or to visit a Gentile; but God has shown me that I should not call anyone profane or unclean.
15: 7After there had been much debate, Peter stood up and said to them, "My brothers, you know (epistamai) that in the early days God made a choice among you, that I should be the one through whom the Gentiles would hear the message of the good news and become believers.
18: 25He had been instructed in the Way of the Lord; and he spoke with burning enthusiasm and taught accurately the things concerning Jesus, though he knew (epistamai) only the baptism of John.
19: 15But the evil spirit said to them in reply, "Jesus I know, and Paul I know (epistamai); but who are you?"
19: 25These he gathered together, with the workers of the same trade, and said, "Men, you know (epistamai) that we get our wealth from this business.
20: 18When they came to him, he said to them: "You yourselves know (epistamai) how I lived among you the entire time from the first day that I set foot in Asia,
22: 19And I said, 'Lord, they themselves know (epistamai) that in every synagogue I imprisoned and beat those who believed in you.
24: 10When the governor motioned to him to speak, Paul replied: "I cheerfully make my defense, knowing (epistamai) that for many years you have been a judge over this nation.
26: 26Indeed the king knows (epistamai) about these things, and to him I speak freely; for I am certain that none of these things has escaped his notice, for this was not done in a corner.