I'm not sure as to civilian police dept. I would look directly to the history of the Dept.in question. Provost Dept. (Military police)operated under the particular dept.assigned,I.E. Dept. of the Cumberland,Dept. of Ohio,Dept. of the Frontier. I know in Chicago usually a new regiment trained at Camp Douglas awaiting field duty would serve as provost.Any regiment might fill the need if ordered as in the Charleston Riots,54IL.Inf.Vols. home on veteran furlough.There was a state provost with military ties operating under the State Adjutant or Attorney Gen..I forget.I would think this includes home gaurd type regiments.I would think the original regimental uniform issued and accrutments would be worn.Possibly an arm band as today. My GGGrandfather was assigned to Provost(Recruiting) and wore his issued 36IL.Inf.Vols. uniform till the end of his muster. These matched the entire union army with few exceptions though.I haven't looked at the O.R. concerning the N.Y. Draft Riots there might be something in Series II Corespondence about Prisoners of War and State.I hope this helps.