What did Peter tell Israel about the Jesus they had killed?
He told Israel that the one they had killed was the one they should have accepted as their king. God raised Him from the dead, called Him back to glory, and was ready to send Him back to still be their king if they would believe that is who He is.
Les explains that Peter, shortly after Pentecost, is still addressing the nation of Israel and is still on covenant ground. Israel had rejected God's promised king by crucifying and killing Him, but God had not given up on them. Peter pleads with Israel that the one they killed was the one they should have accepted as their king. Yet God raised Him from the dead, called Him back to glory, and remained ready to send Him back to be their king if they would believe that is who He is.