Authorities say the killing on March 1, 1976, began after William Bradford Bishop Jr. learned he'd been passed over for a promotion at the State Department earlier in the day.

Bishop had been receiving psychiatric care for depression and suffered from insomnia when, the FBI alleges, he took a hammer to his wife, mother and kids at their home in Bethesda, Md. His wife, Annette; his 68-year-old mother, Lobelia; and three sons — William Bradford III, 14; Brenton, 10; and Geoffrey, 5 — were bludgeoned to death. The boys were killed in their sleep.

Bishop was seen the next day buying sneakers in Jacksonville, N.C., and hasn't been seen since.

But now, the FBI says, the "family annihilator" could be hiding in plain sight in Southern California or in the mountains bordering Nevada. The avid outdoorsman known for his linguistic skills and affinity for Scotch and wine has family in Pasadena and used to talk about his love for the Sierra Nevada, according to the FBI. It's just a matter of someone recognizing him, if he's still alive. He would be 77 today.

Last week, after working with Maryland authorities, the FBI announced it had formed a task force to pursue Bishop and was adding him to the bureau's most-wanted list.

In a rare move, the agency commissioned a sculptor to create a bust of Bishop approximating what he might look like today. Agents hope the widespread publicity of the case will give them the same success they had with convicted mobster James "Whitey" Bulger, who was arrested in 2011 in Santa Monica after 15 years on the run. The FBI had just launched a public awareness campaign for the fugitive when a tip led to his arrest.

In Bishop's case, authorities say some of his idiosyncrasies may tip off a vigilant citizen. The fugitive enjoys peanuts and spicy food and is prone to violent outbursts. He's known for liking a neat, orderly environment and may still have an old Smith & Wesson .38 revolver passed down from his father.

After the slayings, authorities say, Bishop drove the bodies to Great Smoky Mountains National Park in North Carolina, where he put them in a shallow grave and burned them. Authorities say he left his car there.

Bishop worked in the U.S. Foreign Service and speaks English, French, Italian, Serbo-Croatian and Spanish. He earned his amateur pilot's license flying in Botswana and a master's degree in Italian from Middlebury College. He also received a degree in American studies from Yale University and is known for wearing his class ring.

In 1976, Bishop was described as 6-foot-1 and 180 pounds with brown hair and brown eyes. He has a 6-inch vertical surgical scar on his lower back.

There is a $100,000 reward offered for information leading to his arrest and conviction.

joseph.serna@latimes.com