This is so ridiculous. The finder was clearly and without any doubt intentionally trying to start something.  You don't go out and sign logs with ink that can't be seen without a special light if you aren't trying to be "cute".  Grow up.  No CO should be expected to do anything but look at the log sheet and see a signature.     Personally, I feel that any bodily fluid is essentially a biohazard and I would rather people just snap a photo than spit or bleed in my cache.  Again...GR