No kernel panic logs?

[Vulcan]

I'm trying to track down the root cause for random reboots I have been experiencing.  One thing that has me stumped is that I have had zero kernel panic logs.

 

Even when I manually trigger a kernel panic:

sudo dtrace -w -n "BEGIN{ panic();}"

I don't end up with anything being logged in /Library/Logs/DiagnosticReports/

 

Am I missing something here?