This is an excellent point. If the morning Barista or the owners would have known Sam was missing they could have kept the cups, perhaps found-out the ingredients, and LE could have tried for DNA on the cup edges or top opening. Does the



computer log the exact types of coffee sold, or just a general description? It's been a long time since I worked in the bar business, back then we rung drinks up as "rail", "call" or "top shelf", not the specific type.
The problem is that Sam was not reported missing until 1 pm. If I were opening the coffee house and saw coffee cups on the counter and a "mess" I would have dumped the coffee and cleaned up before my shift started. Perhaps LE was able to retrieve the cups from the trash and has tested them for DNA or fingerprints.
I have not seen in MSM an explanation of why Sam wasn't reported missing until the following afternoon.
If my teenage daughter wasn't at work waiting for her ride and never called or text me, I would report her missing ASAP.