They've searched the home & surrounding area to be sure he's not there. It doesn't sound as if there was a basket attached to the bottom, or the parents would have noticed the difference earlier on when they saw a picture.
It was said the door to the compartment was made out of cardboard, not sure, but it sounds like the boy must have fallen out, how horrible.
Holy ****, I just saw this family on TV last night, they were on wife swap, the other family kept hounding them about safety, and how they take too much risk with their kids. WOW, this is going to be horrible for them, they're going to be destroyed by the media.