The Jewish leaders just wanted to kill Jesus for no good reason. This can be translated as, "the Jewish leaders found no good reason for Jesus to die."
## they asked Pilate ##
The word "asked" here is a strong word meaning to demand, beg or plead for.
## When they had completed all the things that were written about him ##
<b>When they had completed all the things that were written about him</b> "When the Jewish leaders did all the things to Jesus that were written in the books of the prophets including Jesus dying"
## they took him down from the tree ##
"Some of the leaders took Jesus down from the cross after Jesus died"