Thousands of artifacts originating from Native American groups and other countries are being packed up and scanned at a rural Indiana farm in an investigation into the collection amassed by a 91-year-old man over eight decades, officials said Wednesday.

Donald Miller has been working with the Federal Bureau of Investigation to sort out whether artifacts he has acquired should be returned to the countries or the Native American tribes from which they came or stay at his Waldron, Ind., farmhouse that has doubled as a makeshift museum.

Dozens of FBI agents, support staff and outside experts in archaeology, anthropology and other disciplines are handling the artifacts. The size of the collection and task before them stunned Larry Zimmerman, a professor of anthropology and museum studies at Indiana University-Purdue University Indianapolis.

“I have never seen a collection like this in my entire life except at some of the largest museums,” Zimmerman told a news conference.

Robert Jones, special agent in charge of the FBI’s Indianapolis office, said Miller may have knowingly or unknowingly violated treaties and state and federal laws in building his collection.

Miller has not been arrested or charged.

“We know that some of the items were acquired improperly,” Jones said, adding that the investigation would try to determine when and how the objects were acquired and whether they were subject to a treaty or statute at that time.

Jones said the collection appears to include Native American artifacts, plus archaeological and anthropological artifacts from China, Haiti, Australia, Russia, Italy, New Zealand, Puerto Rico, Greece, Peru and other countries.

“The cultural value of these artifacts is immeasurable,” Jones said.

It was not clear how the investigation started. An FBI art crimes team member from Indianapolis had information that Miller had items in need of repatriation, Jones said.

Jones did not specify what was in the collection. He said the items would be held until they can be repatriated or returned to Miller if appropriate.

The cataloging and packing at the farm started Tuesday and could last a week, the FBI said.