The investigation, which resulted last week in raids on a Los Angeles gallery and four museums in Southern California, including the Los Angeles County Museum of Art, was known to focus on artifacts taken from protected archaeological sites in Thailand, Myanmar, China and New Mexico. Additional search warrants released by federal authorities show that the investigation also includes artifacts from Guatemala and El Salvador.Investigations into looted antiquities in United States museums have made headlines here for the last three years, but most of those inquiries originated abroad, particularly in Italy and Greece, as those countries sought to recover national treasures they believed had been illegally removed from archaeological sites in recent decades.
The current investigation, however, originated and has so far been conducted mainly by federal agencies in the United States, including the National Park Service, the Immigration and Customs Enforcement office and the criminal investigation division of the Internal Revenue Service. It is one of the largest investigations by American agencies into the business of looted antiquities to date.
The additional documents made public this week include a search warrant for the Malter Galleries in Encino, which the authorities say auctioned artifacts, including many from Central America. The gallery’s owner, Michael Malter, had been told by a federal undercover agent posing as a seller that the artifacts had been illegally obtained.
An affidavit accompanying the search warrant for Malter Galleries also identified a second person, Robert Perez, said to be involved in artifact smuggling. It was Mr. Perez who introduced an undercover agent to Robert Olson, an art dealer in Cerritos, Calif., whose business and clients were at the center of the Southern California raids last week.
Federal agents have also focused on Barry L. MacLean, an art collector and industrialist who is a vice chairman of the Art Institute of Chicago and who maintains a museum, known as the MacLean Collection, in Libertyville, Ill., north of Chicago. Mr. MacLean is chief executive of the MacLean-Fogg Company, a manufacturer of industrial parts in nearby Mundelein, Ill.
According to the federal documents, Mr. MacLean bought artifacts looted in Cambodia, Thailand, Myanmar and Vietnam. They were sold to Mr. MacLean by Mr. Olson, who the court papers say described Mr. MacLean as one of his best clients.
Among the items in Mr. MacLean’s collection said to have been illegally taken from foreign sites were bronze caldrons and ivory and gold earrings from Cambodia, and bronze combs, bracelets and spears from Thailand.
Mr. MacLean was not named in the court papers; he was referred to only as Individual A. But his identity was confirmed by a law enforcement official and another person briefed on the investigation who spoke on the condition of anonymity.
Neither Mr. MacLean, whose involvement in the investigation was first reported by The Los Angeles Times, nor Mr. Malter responded on Tuesday to interview requests left at their offices and sent by e-mail.
A spokeswoman for the Art Institute of Chicago, Erin Hogan, said the museum had no works in its collection donated by Mr. MacLean, although he recently pledged $5 million for the endowment campaign for the Art Institute school.