He told LT. it was intended as a " warning" from the imaginary mobsters that his partner was supposedly investigating.
Remember, the whole scenario is to plant the bogus motivation for his.partners murder.
He wanted the body to be found.
I also think the dumping of the body on the murderer’s lawn was one of the details written on the murder outline Columbo found at the end. Columbo stops reading after he gets to “Bang Bang”, but the implication is that there is much more written there that resembles the murder. So that would make it even worse for Ken.
I've mentioned it before, but there's one area when Ken Franklin does the opposite of overdoing things. Instead of murdering her (especially right away as if he has no choice), he could "stay on the good side" of Lily, who clearly wants HIM at least as much as she wants the money.