Though very different in tone and length, both titles can help non-Japanese people get a bit of insight on how the dead and the people who work with them (pathologists and norikan) are regarded in Japan.

Both stories are gritty, very realistic crime dramas. Both take place in a cold northern Chinese town in the midst of winter. The pace of both stories is slow, it's more about the characters than about the crime itself.
Especially the first few episodes of Double Tap reminded me of Black Coal, Thin Ice -- even though the stories differ greatly, the feeling was kind of similar.