Firstly, "murder" is the unjust taking life from an innocent. When someone is coming at you with a knife in a threatening manner, it's self defense, not murder. Unless you believe that self preservation is not a right we're entitled to.
Secondly, $55,000 (especially in Loudon County) is no where near a "Princely sum", ESPECIALLY when you're tasked with protecting the public 24 hours a day 365 days a year under any conditions and your life is in danger.
This was a completely unjust taking of life.
$55000 is way more that any quick draw killer is worth.