Kohler succeeded Morris as West Berlin station chief after Bentley was captured by Petra Andropov.
In 1973, John Randolph Bentley returned to Kohler's CIA station to be debriefed following his escape from the KGB. Bentley revealed that Dr. Meisner and Petra Andropov were in Krakow, Poland, operating the Cicada program designed to create "human weapons" who would obey orders without question regardless of past loyalties.
This intrigued Kohler, but when Bentley indicated that he himself was forced into the Cicada program, Kohler wondered if the KGB allowed Bentley to escape to return to the CIA as a double agent. Despite Bentley's insistence that he was loyal, Kohler ordered Bentley taken away for psych evaluations, but before he could be detained Bentley fought off two other agents and forced Kohler to cuff himself to a table at gunpoint. He took Frank Ferguson hostage and left the room, after which point Kohler raised the alarm as soon as he could.
Following Bentley's escape, Kohler began grilling Ferguson for any information he might have to help locate Bentley, and even issued a shoot-on-sight order to kill Bentley if he was seen. When Bentley reached out to Ferguson for help, Ferguson reported it to Kohler and os he went along to Ferguson and Bentley's planned meeting. He overheard Bentley admit to killing Dan Ellender, Kurt Jenkins, and Kay Newman, all fellow CIA agents, while under the influence of KGB drugs. Ferguson then brought Kohler into the room when Bentley revealed this.
Kohler admitted that he was now convinced about Bentley's brainwashing story, and confirmed that they did find drugs in Bentley's blood from when he came back briefly. However, when he seemed to be about to shoot Bentley, he suddenly spun and shot Ferguson instead, calling him a "rat" for turning in his own partner. Nonchalant despite having just killed Ferguson, Kohler continued that their ability to force Bentley to kill his own comrades was impressive, and worthy of mimicking to help in the Cold War with the USSR. He tasked Bentley with capturing Petra Andropov due to her knowledge of the Cicada program, and in return Bentley would be cleared of any wrongdoing.
To keep an eye on Bentley's progress, Kohler ordered Wilson, Don Matheson's former partner, to hunt Bentley down and discreetly plant a tracking device on him. Although Wilson died in the process, he completed his mission successfully.
Using Bentley's tracking device to zero in on her safe house, Kohler sent a team to Budapest to apprehend Petra. They then brought her to her safe house, where Kohler himself was inside. He revealed that Petra "betrayed" her, and with no allies left after betraying the KGB, he insisted that she tell him everything she knew regarding the Cicada program. Petra said she'd only talk to Bentley.
After returning to the Berlin CIA station with Petra in tow, Kohler welcomed Bentley back to the CIA when he returned with Don Matheson. Although Bentley claimed he would "burn [Kohler] down" for killing Ferguson, Kohler blithely justified it as a necessity of war and insisted that no proof could be found of his murder. Kohler claimed that Bentley was a hero, and although Bentley tried to leave the CIA, Kohler enticed him to stay to meet his new prisoner, Petra. Kohler watched their reunion, and left with Matheson afterward.