Thou shall not murder is ranked #6 and Thou shall not commit adultery is ranked #7. Even with different numbering conventions, the prohibition against murder is ranked ahead of the prohibition against adultery.
You know I'm not trying to insult you Hitman, but you are mistaken.
Think of the comandments like the bill of rights, not a ranking order.
As I said, both offenses were punishable by death in the old testament.