Busy As A Bee-
There are several famous cases where a lie ended up being far worse than the misdeed it was meant to cover up:
-Richard Nixon lost the presidency due to engaging a cover-up of someone else’s crime.
-Bill Clinton was humiliated, impeached and disbarred for lying to cover inappropriate behavior.
-Best-selling British author Jeffrey Archer was imprisoned for lying to cover inappropriate behavior.
-Baseball superstars Roger Clemens and Barry Bonds are facing prison for allegedly lying to Congress about their cheating.
-Anthony Weiner’s lying about his inappropriate behavior certainly hasn’t helped his cause.
These are just a few cases off the top of my head where lying made thing worse – in some of them much worse – than simply ‘fessing up to the original misdeed.
The specifics of some of the original misdeed are inappropriate to discuss here, and if the girl is a child (as I suspect she is, based on what you said), you will probably have to gloss them over or use a euphemism – e.g. “He took something that wasn’t his”.
I intended to write something in the form of a short children’s story and incorporate one of the above cases, but didn’t have the time – sorry.