So he’s smart enough to know they can track cell phones and link them to crime scenes, just not smart enough to realize that they would track his phone all the way to the scene and leaving from the scene, even if he turned it off when he was committing the crime itself.
Dunning-Kruger in full effect.
I would have loved to have seen the look on Slow-burger’s face when he realized he left the sheath at the scene.