"I don't believe a baggage handler would just randomly go through a bag so suspect it was discovered by security."

Dick this tells me your son has not been completely up front with you. I worked for 36 years for two different airlines and one of the biggest problems in handling luggage is theft. USAirways fired a whole shift (over twenty) baggage handlers in Buffalo one year (several years ago) for setting up an assembly line to go through bags as they went down the belt. The airlines have a security dept. that tries to investigate all complaints of theft even to the point of installing cameras to try to catch the guilty parties. But with that said there is now a new layer of "inspectors" called TSA. There was a time when they recomended that you lock you bag but now that is out the window. The people running TSA at this time recognize the problem and supposely are "working" on it. The airlines and the goverment are at odds as to who pays for the missing items at this time. Until we can go back to "locking" our bags and just have them X-rayed every where we go until they glo we are going to have to not let our personal property out of our sight. By the way they also have complaints of missing items going through with "carry on bags" right under your nose. It is a sad situation that is going to have to change.