The reason why you have a 6.5 kd is because you've killed the murderer 13 times, and died twice.
13/2 = 6.5
Applying these kinds of locks kind of defeats the purpose of having k/d ratios, which are meant to be a more competitive stat to those who want to see them that way. But if the top few players are locked to 1.0 ( or 15.0,) then what's the point?