Murphy

Crap - there's actually three detectives on the Park County Police who've gone by the name of Murphy' or Murphey! Take a look and see if the character you're trying to find is below:

http://southparkstudios.mtvnimages.com/shared/characters/adults/murpehy-mitch-harris.png?height=98
Murphey "Mitch" Harris

http://southparkstudios.mtvnimages.com/shared/characters/adults/lt-murphy.png?height=98
Lieutenant Murphy

There's also another one you see for a second in "The Jeffersons"!