I'm running a group of Cthulhu newbies through "Shadows of Yog-Sothoth". At the end of the first scenario, they more-or-less succeeded. They got the Gate Box in the basement of the Silver Twilight, but put off fiddling with it for a week. This was, I decided, enough time for the matching box (described in the scenario as being in upstate NY) to be collected by Stanford's cronies as they makes their way elsewhere.
In this case, elsewhere was to Europe. To make a long story short, by the time the PCs started experimenting with the box in their possession, Stanford's box was in the state room of a small passenger liner. After a bit of poking around the room, the PCs were surprised, combat ensued, and the trepid heroes dove back into the box and returned to Boston.
One of the PCs who didn't fit in the box had thoughtfully prepared some molotov cocktails, and as soon as the last PC came through the box, he threw the cocktails through and destroyed the box.
I decided this was enough to start a pretty bad fire in the state room, and as the PCs had barricaded the door before escaping, no one would find out immediately... and the liner burnt, then sank.
So my question is: how much SAN loss is appropriate? In their zeal to stop the Silver Twilight, the PCs caused the loss of many innocent lives (a few hundred) of people who just happened to book passage on the same ship as Stanford's assistants. Should the SAN loss be different for the molotov thrower (direct cause) vs. the other PCs? (Accessories to manslaughter?)