The quoted speed in MPH is wrong however.
That's why its wrong.Looks about right to me, although I'm not sure about the decimal places.
Also, don't forget that the speed of sound changes depending on altitude/air temperature.
So rather than expect the system to work correctly, you have to dedicate 20 years of your life hounding policemen, DNA experts, judges, and every other official to get a murder in a small town correctly solved. Kafka would kill himself after 1 month if he were alive now.