Saturday, 5 May 2012

08:13 – Barbara spread about 3,058,180 mL of the mulch yesterday, leaving a gigantic 37 mL (2+ tablespoons) pile of the stuff in the driveway. While she was working, we had Colin on a tie-out in the front yard. Someone came down the street walking a dog, and Colin charged out to see them at a dead run. So much for that collar. The plastic quick-release snap connector fractured. We have a drawer full of old collars, and I was going to replace Colin’s collar with a very robust one that used a standard buckle instead of a quick-release plastic snap connector. Barbara pointed out that if Colin had been wearing one of those he might have broken his neck. So we replaced his collar with another snap connector model.

I finished up the bloodstains stuff yesterday and got started on the group of lab sessions on impression analysis. If I have time, I’m going to add a session to that group. Just about every recent cop show has the cops standing around a whiteboard in the squad room, using dry-erase markers to add information to it. Well, it may surprise some people to know that criminals are also big users of whiteboards and dry-erase markers. And, like most people, criminals usually use erasers to erase the stuff on those whiteboards.

But using an eraser on a whiteboard doesn’t actually erase what’s on it. All it does is remove the microscopically thin layer of dried ink powder, leaving traces of the carrier on the board. Those traces can be dusted with fingerprint powder to make them readable. Although I can’t find anything in the literature about using iodine fuming to make those latent traces visible, I suspect that might work at least as well as dusting. I’ll try it. Meanwhile, smart criminals use a paper towel soaked in isopropanol to wet-erase their dry-erase boards. I’ve already tried that, and found that it makes dusting useless to recover latent traces.