Decepticon is right, it's a medic, if you look closely at the left arm, you can see the white armband with the red + on it, they're also wearing the gray pants that only the medics wear
Now the question is: What caused this? Were the three cops driving along when they smashed into the medic? And where did that one cop's legs go? And where did Headcrab come from? And how in such an open area did such a travesty happen?