I worked in a photo lab at that time (1999). We were required to personally go through each set of photographs to insure quality. We were also supposed to look for bad stuff. Unless we were developing evidence shots for law enforcement, we were supposed to report any photos showing evidence of crimes (including molestations, exploitation, abuse, etc.) to law enforcement. We even removed the kinky sex shots and put in a little slip of paper saying, "We're sorry, but some photographs in this set cannot legally be printed...". Boy, could I tell some stories on what I saw in some people's film sets. :floorlaugh:
In 1999, his best bet would have been Polaroid instant photographs, which were widely available at that time and were generally recognized as the best way to record things that you didn't want others to see.
Now, digital cameras were becoming available at this time, but they were extremely grainy. However, like digital photographs today, you could pull the basic information off of the files (like date downloaded from camera).
I don't recall anyone saying a laptop or hard drive was removed from the trailer, though.