Adult Crime. FBI agent supporting a cop who turns out to have links with a white supremacy group, cop's wife is related to the white supremacy group. Read early 2000s.

[Mrs]

FBI agent/cop moves to a new town, is befriended by a local cop who turns out to be part of a white supremacy group. The cop has nazi tattoo on his scalp, hidden by his hair. The cop's wife is related to members of the white supremacy group. When there's shooting the FBI agent gets people to hide in the bath.
I think I read this in the early 2000s