The family of William Bradford Bishop Jr. is seen on this poster Thursday displayed at Montgomery County Police headquarters. Authorities say Bishop murdered his mother, Lobelia Bishop, 68; his wife, Annette Bishop, 37; and his three sons, William, 14; Brenton, 10; and Geoffrey, 5. (Dan Morse/The Washington Post)

Nearly four decades ago, police say, a State Department Foreign Service officer named Bradford Bishop unleashed a series of vicious attacks inside his Bethesda home. His mother, his wife and his three young sons — all beaten to death with a small sledgehammer.

While it was still dark, Bishop loaded the bodies into the family’s maroon Chevy station wagon, police say, drove 275 miles to a swampy and wooded part of North Carolina, dug a shallow grave and set the corpses on fire. Then, he disappeared.

In a strong indication that Bishop, who would be 77 now, is still alive, federal and local officials announced Thursday that he has been placed on the FBI’s Ten Most Wanted Fugitives list. They portrayed Bishop — an experienced world traveler who was fluent in five languages — as smart, cunning and capable of blending in and building a new life in the United States or abroad.

“Brad, I believe you are likely watching this message,” Montgomery County Sheriff Darren Popkin said into a bank of TV cameras, making a direct appeal to the Yale-educated amateur pilot. “You’ve been living with this on your conscience now for 38 years. I am the voice for your family who can no longer speak. The time is now for you to contact law enforcement.”

Officials also unveiled an “age-progressed” sculpture to show what Bishop’s face might look like today. Police have hunted for him since the 1976 killings, but they said the Web and social media will allow his image and the description of the crime to reach people as never before.

An age-progressed image of what William Bradford Bishop Jr. might look like today. He would be 77 years old. (Courtesy FBI)

Authorities described Bishop’s habits and characteristics from years earlier, saying he might well still have them: An avid hiker and camper, he enjoyed canoeing, skiing and riding motorcyles. He was an avid reader, and he might keep a journal. “He drank scotch and wine and enjoyed eating peanuts and spicy food,” the FBI said in a poster suitable for display in post offices or on Facebook. “Bishop was described as intense and self-absorbed, prone to violent outbursts and preferred a neat and orderly environment.”

Bishop’s inclusion on the list is the latest development in a case marked by stunning violence and international intrigue. Bishop spoke English, French, Italian, Spanish and Serbo-Croatian. He had learned to fly while stationed in Botswana. After his disappearance, there were unconfirmed sightings — a public park in Stockholm, a restroom in Sorrento, Italy, a train station in Basel, Switzerland.

But on Thursday, officials said Bishop could just as easily be in the United States.

“We’re asking the general public to pay attention to the faces they see every day,” said FBI Special Agent Stephen Vogt, head of the bureau’s Baltimore field office. “The men they pass on the street, the co-workers, the guy working out next to them in a senior center, or a man walking his dog in a park, and even — as crazy as it sounds — a family member. Bishop easily could have started a new family.”

Vogt said Bishop may have left Maryland with a Smith & Wesson .38-caliber revolver he inherited from his father; the serial number was C981967. He might still wear the signet ring he received after graduating from Yale. “It’s a gold ring. It had significance to him,” Vogt said.

From the outside, at least, William Bradford Bishop Jr. seemed to have everything going for him in 1976. He was a former football player married to a cheerleader with a degree from the University of California at Berkeley. At dinner parties, Bishop would tell stories of their postings in Italy and Africa.

The couple had three sons: Brad, 14, Brenton, 10, and Geoffrey, 5. Bishop’s mother, Lobelia, 68, lived with the family, in a modern-style home in Bethesda’s Carderock Springs area.

At work, though, Bishop was apparently passed over for promotion, and he told a colleague that the setback had depressed him. Authorities speculate that it might have touched off the violence.

On March 1, 1976, Bishop told his secretary that he wasn’t feeling well and left work early. On the drive home from Foggy Bottom to Bethesda, he stopped at Montgomery Mall and bought a three-pound sledghammer and a gas can he filled at a Texaco station near the mall, according to police. Precisely what may have occurred afterward remains unclear.

At one point during the evening, Bishop’s mother took the family’s golden retriever, Leo, for a walk. Bishop may have attacked his wife first, police say, then his mother upon her return and then the boys. But investigators said Thursday that they cannot be certain about the order of the attacks. What they said they are more sure of is where each person was killed: Lobelia in an upstairs bathroom; wife Annette in a first-floor den; each boy in a bed.

Bishop then allegedly carried the bodies to the station wagon, covering them with blankets, towels and sheets. He drove for five or six hours to the area of Columbia, N.C., in the northeastern part of the state and about 40 miles from the coast.

At 12:40 p.m. March 2, a forest service worker spotted smoke and made a call, which caused a forest ranger to investigate. People who had been building in the area had a habit of burning construction debris, and the ranger thought that was the likely source of the smoke, Montgomery detectives said.

When the ranger didn’t find a fire near the construction, he headed down an old logging road. About 1 p.m., he saw the shallow grave and partially burned bodies.

Popkin, the Montgomery County sheriff, and others believe that Bishop may have fled only minutes before the bodies were discovered.

At 5:30 p.m. March 2, about 130 miles from the grave, Bishop bought tennis shoes at a sporting goods store in Jacksonville, N.C., police said. That was the last sighting of him that law enforcement officials have been able to confirm.

It would take days for authorities to identify the burning bodies and link them to the Bethesda home. Neighbors thought the Bishops had gone on a ski trip, and police did not discover what they described as the “gruesome, bloody crime scene” until March 8.

Ten days later, on March 18, Bishop’s station wagon was found at a campground in Great Smoky Mountains National Park near Gatlinburg, Tenn. Inside the car were bloody clothing and an ax.

“This was a horrific case that involved five innocent members of one family, including three young children, who were all brutally murdered in a place in which they felt safe and by a person whom they trusted,” Montgomery Police Chief Tom Manger said. “News spreads fast and all we need is just one person to call us with the right tip.”

(How to contact the FBI and reward information)

Dana Hedgpeth contributed to this report.