Every person from the first man to the last had a hand in Jesus's death because all have sinned and fallen short of the glory of God. The Jews alone nor the Gentiles alone are responsible, but all are. Don't be confused though, Jesus was not killed by anyone. He laid down His life in perfect sacrifice for the sins of all who would accept His gift. - "For as by one man's disobedience many were made sinners, so by the obedience of one shall many be made righteous."