I was playing a short while ago and was proven for killing a T yet I was RDMed because I refused to get tested. You cant KOS someone for not getting tested can you?
Technically you cannot not. the rules say that you detectives can give orders. however disobeying these orders is not KOSable, you can only be shot for a warning. The rule is below
In the future I suggest that you follow the Detectives orders and test but make sure he stays to show that you are proven
3. -Only detectives can give orders. Disobeying allows the detectives to hurt (but not instakill) as a warning.