The FBI says its phones have been busy since Bishop was added to its "Top 10 Most Wanted List" last week. A $100,000 reward has been offered for information leading to an arrest.
If Bishop is still alive, he would be 77. The FBI has released photos of a bust aimed at showing his possible appearance almost four decades after he was last seen buying sneakers in a store in Jacksonville, N.C., on March 2, 1976.
Investigators say Bishop bludgeoned his wife, Annette, their three sons and his mother in their home in Bethesda, Md., and then drove to North Carolina with the bodies. The next day, North Carolina forest rangers spotted the bodies burning in a shallow grave in thick woods, but they were not identified for several days.
A former Army intelligence officer, Bishop had served overseas with the Foreign Service. The day he allegedly killed his family he had just learned he would not get a hoped-for promotion.
The FBI said agents are operating on the assumption Bishop is still alive. He was last seen buying sneakers and may have had a dog with him.