A massive manhunt 38 years ago in the Great Smoky Mountains National Park is back in the national spotlight.

The FBI has placed William Bradford Bishop on their Top 10 Most Wanted Fugitives list. The U.S. diplomat is wanted for murdering five members of his family in 1976.

The last trace of Bishop was found on the Jake's Creek Trail head at Elkmont in March 1976. According to a Sevier County News Record on March 23, 1976, Bishop's station wagon was abandoned with a shotgun, clothes, a map of Miami and Atlanta, an ax, blood soaked blankets and canvas, and dog biscuits.

The FBI says the story starts two weeks earlier at his home in Bethesda, Maryland, where Bishop's mother, wife, and three sons were beaten to death with a sledgehammer.The boys were sleeping in their beds.

"There was an awful lot of rage. [He] went from room to room with such anger and rage, it was just a terrible crime scene," sai Sheriff Darren Popkin of Montgomery County, Maryland, in an interview with the NBC affiliate in Washington D.C.

ID=7714755The FBI says Bishop drove the bodies in the station wagon to Columbia, North Carolina, where he buried them in a shallow grave and lit them on fire. The bodies were not discovered for another week.

When the station wagon was found, nearly 100 law enforcement officers and rangers scoured the park. They were looking for Bishop who was described as "an avid outdoorsman." Rangers closed the park to campers for at least one day.

The Sevier County News Record said the FBI called off the search on the 23rd day. The items inside the car only led them to more dead ends.

"There's no indication that he's dead," said Steve Vogt, the FBI Special Agent in Charge, to the NBC affiliate in Washington D.C.

Thursday, the FBI placed him on the Top 10 Most Wanted list and released an image of what a forensic artist believes Bishop may look like now at age 77.

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"He may be hiding in plain sight," Vogt said at a news conference Thursday.

For law enforcement who've been working the case for decades, finding him is personal.

"Brad, you've been living with this on your conscious for 38 years now. I am the voice for your family that can no longer speak. The time is now for you to contact law enforcement," Sheriff Popkin said at the press conference.

The FBI said Bishop is a graduate of Yale University and spoke five languages fluently. He was working for the U.S. State department when he went missing.

The FBI suspects he is still living in the U.S. with a different name.

If you have any information, you can contact the FBI at 1-800-CALL-FBI. The agency is offering a $100,000 reward.