It’s a life explored, as much as one can explore a life mired in obfuscation, by Colby’s son, Carl Colby, in “The Man Nobody Knew: In Search of My Father, CIA Spymaster William Colby.” The documentary screens Thursday night at the Oklahoma City Museum of Art.

Despite the familial connection between documentarian and subject matter, filmmaker Carl Colby takes a somewhat standard documentary approach profiling his father, who died in a 1996 boating accident. The movie employs archival footage and photos, interspersed with interviews ranging from Colby’s former colleagues, such as James Schlesinger and Brent Scowcroft, to heavyweight journalists Seymour Hersh and Bob Woodward.

Most interesting are Carl Colby’s comments, which he delivers in an informal voiceover as if narrating a slideshow of home movies — except that these home movies document an intelligence officer who was at the heart of Cold War intrigue. “My father, he did a lot of things, but he was always very good at making war,” Carl Colby states early on.

The elder Colby was a born soldier. With the CIA from its very beginning, William Colby used the cover of foreign diplomat for covert assignments that sent him and his young family hopping across the globe. Following WWII, Colby was stationed in Italy to keep watch on that country’s increasingly popular Communist Party.

In 1959, Colby moved to South Vietnam to help the government of Ngo Dinh Diem against communist insurgents backed by North Vietnam. The tight-lipped American developed a close friendship with Diem’s brother, Ngo Dinh Nhu. Colby was consequently devastated when the brothers were murdered in a 1963 coup. Colby remained ensconced in the Vietnam conflict, eventually coordinating the controversial counterinsurgency strategy, Phoenix Program.

Most Americans came to know Colby in the mid-1970s. Then director of the agency for which he had devoted most of his life, he testified before Congressional hearings that cast an harsh spotlight on the CIA’s shadowy web of secret prisons and political assassination.

As a documentarian, Carl Colby has the benefit of an absorbing subject at the center of a tumultuous time in modern U.S. history. As a storyteller, however, his skills are uneven. The film’s section on Vietnam veers into a laundry list of U.S. miscalculations during the war, much of which has been well-covered elsewhere.

More problematic, the filmmaker gets fuzzy on a few pivotal life events — particularly the death of William Colby’s daughter — that the work contends are essential to understanding its central subject.

“The Man Nobody Knew” ultimately doesn’t really crack the enigma of William Colby, whose emotional aloofness left few clues for his son/profiler. Still, the documentary is an often-fascinating window on the world of a real-life secret agent man.