
Kleiner would later take employment in the Sector C of the Black Mesa Research Facility, where he worked with Eli Vance and security guard Barney Calhoun. It appears that the two started their friendship already back then, and that Kleiner was quickly impressed by Freeman. Kleiner first worked as a professor at MIT, where he was one of the mentors of Gordon Freeman.

The second page of L.M.'s letter, where Kleiner is mentioned for the first time.
