In this concluding verse of the second scene, Good News Translation has done considerable restructuring:
(1) Knew is given the English idiomatic equivalent “knew very well” (similarly Die Bibel im heutigen Deutsch, Bible en français courant).
(2) They are fully identified as “the Jewish authorities,” (Good News Translation) though on the basis of verse 12 it is also possible to render “the chief priests and the elders.” (Die Bibel im heutigen Deutsch retains the impersonal force of the Greek by translating they as “one.”)
(3) “To him,” though not in the Greek text, is introduced for the sake of clarity; it will be required in some languages.
(4) The noun construction out of envy (New Jerusalem Bible, New American Bible “out of jealousy”) is altered to a verb construction, “because they were jealous.” But even this may have to be expanded in some languages to “because they were jealous of Jesus.”

Quoted with permission from Newman, Barclay M. and Stine, Philip C. A Handbook on the Gospel of Matthew. (UBS Handbook Series). New York: UBS, 1988. For this and other handbooks for translators see here .