“Summer Clouds” by Edgar Payne was stolen in 2006 and found by the FBI

Ralph Ekberg was asleep when the thief sneaked into his room at a Springfield nursing home and lifted his favorite painting from the wall three years ago.

Ekberg treasured the artwork he’d purchased in 1965 for $400, although he had no idea of its current value.

Neither did the thief, who figured he might make a few hundred dollars by posting it for sale online.

He was wrong.

A California gallery offered $175,000 for the work by renowned American impressionist Edgar Payne called “Summer Clouds.”

With no proof of ownership other than his word that the painting belonged to his uncle, the thief shipped the 20-by-24-inch oil-on-canvas work to the West Coast and began enjoying his ill-gotten bonanza.

After the theft was reported, Springfield police turned to the FBI and its art crime team of specially trained agents to help track down the pilfered painting.

The art crime team formed in 2004 to combat the multimillion-dollar trade in stolen art and items of cultural and historical significance that transcends international boundaries.

It has recovered more than 1,000 items worth more than $135 million.

The team’s 13 agents have investigated everything from the theft of Elvis Presley memorabilia to pre-Columbian South American artifacts to works by masters such as Rembrandt and Goya.

“It’s very, very common for the crime to cross state and international borders,” said Bonnie Magness-Gardiner, manager of the FBI’s art theft program. “The U.S. is a huge market for art and cultural property.”

The FBI maintains a stolen-art database that now contains about 7,000 items. The database currently is available to law enforcement agencies, but Magness-Gardiner said it soon could be available to the public.

Though sophisticated heists at museums garner big headlines, most art thefts in the United States occur in run-of-the-mill burglaries, she said.

“For the most part, the criminals don’t know how valuable something is,” she said.

Tracking stolen items can be difficult because the United States has no law requiring specific ownership documentation for valuable works of art.

“It makes it easier to insert stolen items into the legitimate market,” Magness-Gardiner said. “It’s up to each gallery and buyer to exercise due diligence and common sense.”

Even when a stolen item is recovered, legitimate owners can have a difficult time getting property back without proper documentation, she said.

That can lead to lengthy and expensive civil litigation such as the lawsuit pending over another painting stolen decades ago in Missouri and recovered in 2007.

“Russian Schoolroom,” painted by Norman Rockwell, was stolen in a 1973 burglary in Clayton, Mo., and ended up in the collection of film director Steven Spielberg, who bought it in 1989.

Spielberg exchanged the work for another Rockwell painting from one of multiple claimants now battling in court for ownership.

Mary Ann Johnston hopes “Summer Clouds” won’t end up in the same kind of legal tangle.

She is a cousin of Ekberg, who died in 2006 at the age of 91, a few months after the painting was stolen from his room. He left the painting to Johnston as part of his estate.

The theft investigation led authorities to a former nursing home employee, Micah Owen Shatswell, who was indicted by a federal grand jury in December for transporting the stolen painting across state lines.

He pleaded guilty April 9 and faces up to 10 years in prison.

The gallery that bought the painting from Shatswell sold it to a Minnesota woman.

Johnston said that “quite by accident” she found the original certificate of purchase in Ekberg’s papers. She has hired an attorney to help her recover the painting.

She said neither she nor Ekberg knew how valuable it was. Ekberg was not an art collector but owned a few paintings. She said “Summer Clouds” was always his favorite.

When she gets it back, Johnston is not sure whether she will keep it or sell it. Now that she knows its value, she said, it would make her nervous to have it in her house.

“If I do keep it, I’ll definitely insure it,” she said.