Having been a pastor for 40 years, this is a tough call.
Having been a "high-office" layman for as many, and an LEO as well, I've thought this through several times. Can a Christian legitimately be a cop? Can a Christian non-cop legitimately be a shooter?
Romans clearly points out that the "state" has the "power of the sword."
Non-cops must rely on something more general. I see it in a relatively simple way:
I believe in both literal God and a literal Devil. I see a long term controversy between them, carried out primarily on our planet. Having chosen to limit himself by choice, God has given "earthlings" the power of choice. Having used that choice badly they have come under the "banner" of God's enemy - the literal Devil.
Having given "earthlings" the power of choice, God must honor it. For them, that means they "suffer the consequences" of their choice. For God, that means the classic quandary of good versus evil. The out here is another quandary, justice versus mercy.
To make sense, God must end evil. But having given the power of choice he must allow evil. The solution is to let evil "run its course" as proof of its unacceptability, but end it when the time is right. At the same he must not to let those who wish to rejoin God's side be simply wiped out. Thus we see him protecting his loyalists "to an extent," but not taking them out of the real world. A major juggling act. The real world attacks anyone, loyalists and rebels alike showing proof of the "badness of bad."
Since God has limited his own options and permitted evil to play itself out, history hasn't been ended yet. The good book shows a sorry picture indeed of what eventually happens here and how the "loyalists" are finally rescued.
But since things are still in a state of flux, we must help ourselves in many cases and many ways.