"Wire in the Blood" is excellent for a cop show where one of the main characters is a forensic psychologist. English.
Some Danish, Swedish and Swiss cop shows I have watched are excellent as well. "The Eagle" from Denmark(I think) was brilliant.
"Spooks" which is about MI5 is also brilliant. English.
"Waking the Dead". English. Large forensic componant.
"Murphys Law". English with Irish actor James Nesbitt who is also a spunk
Not sure if that matters to you
and
"Silent Witness" which is more a forensics based show but cop stuff in it. Harry Cunningham is Devine
English.
I very rarely invest in American cop shows (sorry my US buds
) but Law and Order isn't too bad for light weight stuff. We had "The Wire" here but I couldn't seem to get into it and then I lost track of what was going on.
Hope that helps.
Loup