Three days after her disappearance, Fred was sure Maura had run away. There's no mention of foul play, that he talks about later. At that time, he's sure she's run away, even though the only real evidence anyone has at that time is that she got into a wreck, was alone for less than 10 minutes, and has not been seen again.
Even in light of the ATM withdrawal and the note to her teachers explaining she was leaving, her car has been found abandoned in the middle of the North Country. And she's missing.
What does he know that makes him so sure she's run away from the crash site? What motive would cause Maura to run away, not just from school, not just the accident, but from him as well?