Officer Curtis is a rookie, out on his own for the first time. He pulls over a car. The driver is falling down drunk. He arrests the driver, and puts him in the back of the patrol car. However, wanting to show himself worthy of working on his own, Officer Curtis decides to handle the call completely by himself. He calls for no help. He locks the driver's car up, and takes the drunk to the station for booking.

The next day, the Chief has you, Officer Curtis' sergeant in his office. Apparently, the drunk was a rich businessman and friend of the Chief. The drunk's/businessman's car was stolen and found in a quarry, minus $10,000 in cash he had yet to deposit and a gun he legally possessed.

You are ordered to counsel Officer Curtis on inventory searches. Specifically you are to tell him why they are reasonable, why he doesn't need probable cause, and for what purposes he should be doing them for. 

Explain inventory searches in light of Officer Curtis' actions.