LOS ANGELES — Federal agents raided a Los Angeles gallery and four museums in Southern California on Thursday, including the Los Angeles County Museum of Art, as part of a five-year investigation into the smuggling of looted antiquities from Thailand, Myanmar, China and Native American sites.The other institutions searched were the Pacific Asia Museum in Pasadena, the Bowers Museum in Santa Ana, the Mingei International Museum in San Diego and the Silk Roads Gallery in Los Angeles.
At the center of the investigation are the owners of the Silk Roads Gallery, Jonathan Markell and his wife, Cari Markell, and Robert Olson, who is said in the search warrants to have smuggled looted antiquities out of Thailand, Myanmar and China.
In affidavits supporting the warrants, federal agents said the Markells had imported looted antiquities provided by Mr. Olson and then arranged to donate them to museums on behalf of clients who took inflated tax deductions for the gifts.
No charges have been filed in the investigation, which was described as continuing by a spokesman for the United States Attorney’s Office in Los Angeles. The inquiry is being conducted by the Immigrations and Customs Enforcement office, the National Park Service and the criminal investigation division of the Internal Revenue Service.
Even though looted antiquities have been the subject of recent investigations here and in a high-profile prosecution in Italy of a former curator at the J. Paul Getty Museum in Los Angeles, the raids were a startling development. Most recent investigations involving museum collections have involved objects excavated in Italy or Greece.
The affidavits accompanying the warrants detailed meetings between an undercover agent for the National Park Service, who for years posed as a collector, and the Markells and representatives of some of the museums.
In cases involving at least two institutions, the Bowers and the Pacific Asia museums, the affidavits say curators appeared to be aware that the objects that they were accepting as donations had been looted or illegally imported.
The affidavit describes a process in which objects were smuggled after being painted or affixed with stickers reading “Made in Thailand” to make the pieces look like replicas.
Several of the museums have objects in their permanent collections that were donated by the Markells or their clients, according to the affidavits. Michael Govan, the director of the Los Angeles County Museum of Art, said at a news conference that the museum had about 60 objects related to the investigation that had been donated by the Markells or other museum members over the last decade.
Mr. Govan said the museum was fully cooperating with the authorities. He also defended the museum’s process for reviewing potential donations, noting that in the affidavit Mr. Markell is quoted as warning the undercover agent away from a donation to the museum because officials there “were sticklers for having good provenance.”
Yet the affidavit also cites a statement by Mr. Markell that the museum had been able to get around the ban on imports of Thai artifacts because it “had found a loophole” in the law. One such discussion involved a vessel from the Ban Chiang culture in Thailand that the museum was interested in acquiring, according to the affidavit.
Mr. Govan denied that the museum knew of such loopholes or had looked for them. “There is no loophole that we know about,” he said. “If anybody can identify one, we would be the first to close it.”
Mr. Govan said no objects had been removed from his museum on Thursday by the investigators, who in the warrant said their intent was to review and copy computer records regarding donations by the Markells or their clients. But search warrants for some of the other institutions included artifacts that were to be seized.
Heidi Simonian, a spokeswoman for the Bowers Museum, said that it was cooperating with the authorities but that no officials were available to comment. Peter Keller, the director of the Bowers Museum, and Armand Labbé, a former curator of the museum who died in 2005, were said in the affidavits to be aware that some of the donated objects had been illegally acquired.
Ms. Simonian said she was not aware whether agents had removed any artifacts from the Bowers Museum.
Rob Sidner, the director of the Mingei International Museum, said in a statement that if the investigation showed that any of the artifacts in its collections had been improperly donated, “we will return them to the rightful owners.”
Representatives of the other institutions and the Markells did not return calls seeking comment on Thursday.
According to the affidavits, the undercover agent made as many as 10 purchases of items stolen from Thailand or illegally imported from Myanmar. The Markells also showed the undercover agent a collection of antiquities that they said had been stolen from China, the authorities said.
In more than 120 pages of search warrants and affidavits, the authorities described one typical transaction as follows:
The Markells would acquire an object from Mr. Olson and then offer it for sale to the undercover agent for about $1,500. They would provide an appraisal valuing the object at close to $4,990, an amount calculated to get around tax regulations requiring more documentation for bigger donations. The appraisals sometimes falsely stated that the estimated values were prepared at the Southeast Asian Museum in Bangkok. The Markells would then arrange for the donation of an object to a museum.
In addition to the South Asian antiquities, objects taken from the Chaco Culture National Historical Park and El Malpais National Monument, both in New Mexico, were also cited.