This just started airing on the Showcase channel in my Canadian city. It's produced by BBC America so now doubt it's being carried in the US. Unfortunately I only caught the last 20 minutes due to the network being incorrect in their ads about their PST time slot,
but what I caught looked quite good. It's main protagonist (played by Tom Weston-Jones) is an Irish Immigrant policeman named Kevin Corcoran, who uses state of the art 19th century forensics to solve crimes. It's the same 5 Points New York neighborhood of the 1860's that was also the setting for Scorcese's Gangs of New York.
The subject matter of the episode was very dark and the whole style and presentation of the setting echo'd that - heck it made Gangs of New York look almost cheery. Corcoran uses hardline tactics very much like law enforcers in Gangs of NY did, and some of them seemed pretty damn brutal. I'm not sold too much on the lead actor, but what little I saw of the rest of the cast was good. I loved Gangs of NY, so I'm looking forward to catching more of this.