Pulling back a small black velvet curtain on Tuesday, Minnesota's top FBI supervisor finally unveiled the long-lost pair of ruby red slippers purloined from the Judy Garland Museum in Grand Rapids, Minn., more than 13 years ago.

Jill Sanborn, special agent in charge of the Minneapolis division, couldn't resist her own Oz-inspired pun — "And now, under the rainbow" — before the big reveal. But she also had a plot twist in store for what has become an enduring saga: The culprit who swiped them is still out there.

One of four pairs worn by the actress in the 1939 classic film "The Wizard of Oz," the stolen slippers were found during a July sting operation in Minneapolis, authorities said Tuesday. The break came about a year after Grand Rapids police fielded a tip that proved more fruitful than past rumors of the slippers being tossed in a flooded iron ore pit or turning up at a roadside diner in Missouri.

Though officials declined to elaborate on the tipster, the FBI deployed agents to carry out search warrants in Minnesota and Florida while working what Sanborn described as "still a very, very active and ongoing investigation" into the theft and "more recent scheme to defraud and extort" the insurance company that owns the slippers.

No arrests have been made public, but the FBI said it has identified suspects in the plot. On Tuesday, attention turned to the still-glittering pair of red-sequined slippers resting safely inside a glass case.

"This is a significant milestone," Sanborn said. "[But] while we gathered lots of information on this case, we believe there's lots more to give."

The slippers — thought to be valued in the millions of dollars — were stolen overnight while on loan from Hollywood memorabilia collector Michael Shaw to the Judy Garland Museum on Aug. 28, 2005. A single red sequin and shards of broken glass were all that were left behind. Museum officials at the time said an emergency exit behind the building had been tampered with.

Now considered criminal evidence, it's unclear when the slippers will re-emerge in the public eye. Rhys Thomas, author of "The Ruby Slippers of Oz" and a close watcher of the mystery, flew from California to attend Tuesday's announcement and predicted that the slippers could fetch up to $7 million if they are ever up for auction again.

Other pairs of slippers belong to the Smithsonian National Museum of American History, the Academy of Motion Picture Arts and Sciences and to a woman in Tennessee who won her pair at a contest in 1940, Thomas said. He suggested that the newly recovered pair will likely soar in value because of its mysterious disappearance.

Those same slippers also previously faded from view for 30 years after their use in the film, Thomas said, before a Hollywood costume designer secreted them away from storage and Shaw came up with $2,500 to buy the pair. The Markel Corp. later bought the rights to the slippers from Shaw for $800,000 and has been assisting the FBI investigation.

Before Sanborn lifted the curtain on the slippers Tuesday, Grand Rapids Police Chief Scott Johnson described the recovered artifacts as "more than just a pair of shoes or slippers … they're an enduring symbol of the power of belief."

That symbolism cuts two ways, Thomas said. For one, they represent the magical red slippers that in the movie fulfill Dorothy's wish to go home.

"And then there's Judy Garland's ruby slippers, which are the Holy Grail of Hollywood memorabilia," Thomas said. "They connect this iconic star to an iconic movie that everyone seems to remember and wants to feel a part of in some way."

Garland's Minnesota roots

Garland, born Frances Gumm, lived in Grand Rapids until she was 4½, when her family moved to Los Angeles. She died in 1969.

Word of the slippers' recovery traveled fast by early Tuesday morning, beginning with a joyous Facebook post from the museum broadcasting to its followers: "It's true! The RUBY SLIPPERS have been found! … We can barely believe this news!!!!"

Lilah Crowe, director of the Itasca County Historical Society, described a feeling of relief in a community that had come to advertise the site of the 2005 theft rather than the presence of a pair of slippers once on display in Garland's hometown.

"It has always been that feeling of incompleteness," Crowe said.

The Smithsonian's museum of American history examined and authenticated the pair recovered in Minneapolis, the FBI said. Conservators found the Minnesota pair's construction, materials and wear to be consistent with the pair in the museum's collection.

North Dakota's U.S. attorney, Chris Myers, has been assigned the case, though officials declined to elaborate on why his office would be responsible for any charges filed in what the FBI described as an "extortion plot" against the Markel Corp. The FBI's specialized Art Crime Team investigators have been assisting law enforcement throughout the probe.

Though more work is ahead for investigators, Crowe described a feeling of relief washing over Grand Rapids upon hearing Tuesday's news and the revelation that the slippers are still in good shape. The historian hopes the story of the slippers doesn't go forgotten.

Who knows, she said, maybe it will be the subject of a movie one day.

"Hopefully they'll do it here," she said.