One day in 1975, college student Jay Bruder walked into the Northeast American Rescue League thrift shop on H Street NE and flipped through the records for sale. Elvis Presley’s first album was there — score! — but so was something less familiar.

It was a 10-inch 78 rpm record with the word “Atlantic” on a black label.

“Now, Atlantic 78s are red,” Bruder, 65, told me recently. “I've never seen a black label.”

Bruder figured that the music on the record was modern jazz, not a genre that interested him particularly.

“I put it back,” he said. “What a fool. That might have been the very first Atlantic record. All these years later, I’ve never seen another copy. ... That’s the Holy Grail for me, if I could again see the record I passed up at the Northeast Rescue League in 1975 on a cold winter’s day.”

All collectors have their Holy Grails, those objects of obsessive desire. Bruder’s include things you can hold in your hands, like that record, but also things you can’t. For decades he’s been trying to track down every last fact connected with the early rhythm-and-blues music scene in Washington.

I’d say he’s done a pretty good job. Last fall, Bruder’s magnum opus came out on Germany’s Bear Family record label. It’s a 16-CD box set titled “R&B in DC: 1940-1960” that gathers hundreds of songs from dozens of bands with Washington connections.

The accompanying 352-page hardcover book is a lavishly illustrated history of bandleaders such as Thomas “TNT” Tribble, “the walking drummer,” and Frank Motley, who played two trumpets at once.

There are close-harmony singing groups like the Clovers, the Rainbows and the Blue Jays; venues like the Howard Theatre and the Crystal Caverns; and homegrown record labels such as Scoop, DC and Paragon.

“I did it for the artists and their families, so they would get the recognition,” said Bruder, who lives in Fairfax County. “One thing I've never understood is why my generation and later didn't remember these people. It was more actively not remembering them than passively. It was like this music got buried.”

Bruder is an unlikely archaeologist. As the son of a U.S. Marine, he grew up around the world. The Washington area was always the family’s home base.

“I came home from Beirut in 1970, totally adrift,” he said. It had been hard to keep on top of current American music from such a remove. But when Bruder returned to the States, the ’50s revival had started.

“It was kind of neat to hear this old music, which I kind of remembered from the first and second grade,” he said.

In 1974, Bruder graduated from Alexandria’s Fort Hunt High School. He went to college — first in Beirut, before civil war broke out, finally graduating with a history degree from Georgetown — then joined the Marine Corps himself.

He had a 31-year career in the military, including combat deployments and intelligence work. There were surprising overlaps with his search for musical intelligence. Said Bruder: “Let’s just say that years of writing military documents enforced a level of rigor.”

I can attest to his drive for detail. Last year I wrote about 99-year-old Howard Stokes, one of the District’s first African American streetcar operators. Bruder was gathering information on a song called “Big Sid” by the 3 of Us trio, featuring vocals by Charles Kelley.

The song is apparently about the trolley — a lyric goes “Can you ride, ride, ride Big Sid?/You ride Big Sid and you might get thrown a mile” — but is it about a particular streetcar or driver? I put the question to Stokes. He had no memory of Big Sid, but it was a testament to Bruder’s sleuthing.

At $260, “R&B in DC” isn’t cheap, but time machines tend to be expensive. And that’s what this is: a time machine that takes the listener and reader into the past. I lost myself in its sounds and sights.

On Sunday evenings, Bruder hosts a show with a special emphasis on Washington music at the website BluegrassCountry.org. And he continues to seek out musical Holy Grails.

“What I would love to find are some actual air checks of African American DJs on the air in D.C. in the 1950s,” Bruder said of those bits of patter disc jockeys delivered between the records they spun. “There must be a few of those.”

He craves old records with D.C. connections. And photographs of D.C. groups. And, more than anything, he seeks information.

One of Washington’s biggest R&B mysteries is a group called the Eagles, represented on the box set with nine songs. They were supposedly discovered at a club around Florida Avenue and Seventh Street NW.

“I have never found a newspaper clipping that gives us the dates of their performances,” Bruder said. “We don't have a photograph of them. We don't have any names for the group members.”

Perhaps the memories are still out there, as vibrant in someone’s mind as Bruder’s memory of that black-label Atlantic 78.

Read more from John Kelly.