GK,
Some drug tests only test for some drugs and not others. Generally speaking, the cheaper the test, the less it tests for.
Also, some drugs are out of the system within a weeks time.
He may also have bought some of the stuff at the health food stores that claim to clean out the system. Some work better than others.
Any of these senerios would explain this man's ability to escape the consequences of his actions and get away with seeing his daughter.
It's a shame.
I do hope his daughter never has to pay the price for his actions...
Shalom!