Updated

The killer had a grudge against the Pennsylvania State Police, regularly visited a local shooting range to keep his skills sharp, and picked just the right hiding spot from where he could launch an ambush and make his escape.

This chilling profile was developed by state police searching for the gunman who opened fire on two of their own outside the Blooming Grove barracks late Friday. It was released to the public Monday in hopes it might help authorities catch him.

Authorities say the unknown gunman used a .308-caliber rifle to kill Cpl. Bryon Dickson and critically wound another trooper at the remote outpost surrounded by dense forest. He then slipped away. The motive is unknown, but police said Monday it's likely he had a grievance against the state police.