Johnston was a former military officer assigned as the Director of Psi Corps following the departure of Director Kevin Vacit in 2195.[1]
As was the tradition at the time, Johnston was a normal rather than a teep and was particularly distrustful of the Telepaths under his command and wasted no time in tearing down many of the things Vacit had put in place, starting with his chief Lieutenants. Johnston was particularly suspicious of Alfred Bester, a Cadet that Vacit was known to have taken a special interest in, though his reasons for doing so remained a mystery, even to Vacit's closest confidants.
In 2256, Johnston tried to have Bester killed, but Bester survived the assassination attempt. Bester then took his revenge upon Johnston by setting off a bomb on Ganymede that killed the director. The bombing was blamed on the rogue telepaths.