Now let's see if we can find a smoking gun or in this case a smoking pair of blue jeans. If you look closely at the picture below, you will see a key sticking out of the pocket.
The jeans belong to this Robert De Niro wannabe =>
The mystery is solved!
Why was it so tricky? Why didn't Mild-mannered Mom look in the clothes hamper in the first place?
She did not take into account the fact that all teenagers chose 3 outfits every day. The jeans were perfect for an early morning trip to the van, but not "cool" for the ultra fab folks in IB English.
Hence Teenaged Son # 1 returned the still pristine jeans to the clean clothes pile by the dryer. Ahhhhh.