New York, United States —A priceless Stradivarius stolen 35 years ago from an American concert violinist was back in the hands of his heirs  -- a happy ending to a long-running mystery cracked by a luthier's keen expert eye.

The violin -- made in 1734 and estimated to be worth $5 million -- had been lifted in May 1980 from the office of Roman Totenberg at the Longy School of Music near Boston, where he taught.

Totenberg died in 2012 at the age of 101 after a life that saw the Polish-born virtuoso, who emigrated to the United States in 1938, perform with a host of major American symphony orchestras.

"Our only sadness is that our father is not here to see this," said his daughter, NPR public radio justice reporter Nina Totenberg, as federal agents returned the violin at a ceremony in New York.

"But I think he is somewhere with my mother," she said, "celebrating with a shot of vodka."

In an NPR blog, Totenberg said she got a telephone call from an FBI agent in June, informing her that the violin -- known among aficionados as the Ames Stradivarius -- had been located.

It had been discovered by the widow of a musician named Philip Johnson -- who died in 2011 -- stashed inside a locked case inside their home, she wrote.

The elder Totenberg had suspected Johnson from the outset to be the thief, but police chose not to pursue the lead, she said.

The widow took the instrument in June to Phillip Injeian, a violin maker and appraiser, who examined it closely for a half-hour in a New York hotel room.

"Well, I've got good news for you, and I've got bad news for you," Totenberg quoted Injeian as telling the widow.

"The good news is that this is a Stradivarius. The bad news it was stolen 35, 36 years ago from Roman Totenberg."

- Promptly reported - 

Injeian promptly reported the violin to the FBI's art theft unit, and Johnson's widow relinquished any claim of ownership to the instrument.

"There is a label inside ... dated 1734," explained Injeian at Thursday's handover ceremony in the office of Manhattan federal district attorney Preet Bharara.

"But what was really a giveaway ... were the characteristic markings of the wood. It's like a fingerprint. You can't forge that."

Nina Totenberg said she and her sisters Jill and Amy intend to sell the Stradivarius in hopes that it will once again charm concertgoers in the hands of another great virtuoso violinist.

"None of us play the violin," she said, "and Stradivarius owners are really just the guardians of these great, great instruments. They are meant to be played by great artists."

Around 550 of the highly coveted violins handcrafted by Antonio Stradivari still exist, Injeian said, out of a total 1,100 by the 17th century Italian master craftsman.

They are highly prized for their incredible -- and inimitable -- sound. Many have experienced some remarkable adventures over the centuries.

One, known as the Lady Blunt, fetched about 11 million euros ($13.5 million) in a 2011 charity auction for victims of the Japanese tsunami.

In January 2014, a Stradivarius was snatched from the concertmaster of the Milwaukee Symphony Orchestra in Wisconsin by muggers armed with a stun gun. It was recovered in a matter of days.

In July 2012, a Stradivarius was turned in to a Swiss railway lost-and-found counter after an acclaimed violinist forgot it on a commuter train.

And in 2008, an American violinist left a $4 million Stradivarius in the back seat of a New York taxi. The driver returned it to its owner.