Merciful to the Last..
It is not only the sin but also the attitude of the sinner that Jehovah notes.
{Isaiah 1:16-19}

Reflect for a moment to the two evildoers impaled alongside Jesus.
Both had evidently commited serious crimes, for one of the men admitted:
" We are recieving in full what we deserve for the things that we did; but this man {Jesus} did nothing out of the way."
The evildoers words indicated he new something about Jesus.
And that knowledge likely contributed to a wholesome change in his attitude.