There are no police snipers in GTA iv. However, there are some missions that appear to have police snipers; like in Three Leaf Clover where the NOOSE are shooting down at the protagonist from the fire escapes. Also, some say that police helicopters have officers that snipe at the player from the sides of the chopper, but that is also false. The guns they use are assault rifles. In the TBOGT there are police snipers on top of high rise buildings near and around the downtown area in Algonquin, they use the automatic sniper from the GTA IV original.