(Back in May, his passenger door got dented. He claimed it was because a car hit it in the parking lot. My dad and I couldn't figure out how a car could produce that kind of dent while leaving that kind of residue, so my dad went investigating and found that there was red paint on the entry edge of his old garage at the apartment where he more likely tried to enter the garage and didn't know the dimensions of his car and so caused his own dent but was too ashamed to admit to me. He never has fessed up to that one to me, though he did acknowledge that my dad was right when my dad confronted him)
I'm sorry, from this it sounded like you and your Dad went investigating. Nonetheless, your Dad shouldn't really be investigating your husband, he's an adult.