A philosophy professor at St. Cloud State University pleaded guilty Tuesday to illegally dealing in goods made from elephant ivory and rhinoceros horns worth up to $1.5 million in a case that wildlife authorities say is one of the biggest they've investigated in Minnesota.

Yiwei Zheng, 43, was indicted by a federal grand jury last year after prosecutors accused him of smuggling the items, which are covered by federal wildlife laws, from the U.S. and into China from 2006 to at least 2011.

Investigators used seized records from Zheng's home to establish the fair market value of the goods at more than $1 million, according to Assistant U.S. Attorney Laura Provinzino. As part of his plea agreement, Zheng agreed that the items were worth between $550,000 and $1.5 million.

"The extent and scope of the value at issue here makes this unique," Provinzino said.

Timothy Webb, an attorney for Zheng, said his client was guilty of failing to obtain permits under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) to deal in goods that contained elephant ivory or rhinoceros horns.

Webb said the items at issue are 50 to 100 years old and were made before the elephant and rhinoceros were considered endangered species.

"The vast majority of it had Chinese historical or culturally artistic value," Webb said.

Zheng also admitted that he knowingly failed to declare the items to wildlife or customs officials as required when importing or exporting wildlife. In one case, investigators found that nearly $7,000 in elephant ivory items purchased from eBay had been declared by Zheng to be worth just $35 on the exported shipment.

An investigation by U.S. Fish and Wildlife Service agents also found evidence that Zheng bought two rhinoceros horns from Florida for more than $20,000 and smuggled them out of the U.S. to China, where they were sold at auction for roughly $68,000.

Prosecutors have said that Zheng made false statements to agents during the investigation.

Guilty on two counts

Free on $25,000 bond, Zheng pleaded guilty to two of the six counts on which he was originally indicted: smuggling elephant ivory and illegally exporting rhinoceros horns from the U.S. in violation of the Lacey Act. Under the 1900 law, the first federal wildlife protection law, it is illegal to transact in any wildlife, fish or plants taken in violation of a state, federal or foreign law.

"Importing and smuggling does have a direct impact on the poaching happening now in parts of Asia and Africa for these items," Provinzino said. "There just aren't adequate law enforcement resources on the ground [in those countries] to deal with this."

A spokesman for the Fish and Wildlife Service in St. Paul said the overseas value of such items has spiked by three- or fourfold recently.

"The recent affluence in China has caused a lot of excess demand for these items," said Pat Lund, special agent in charge at the U.S. Fish and Wildlife Service in St. Paul. "The prices in China and Southeast Asia have skyrocketed and led to increased smuggling in the U.S. and Europe and increased slaughter of elephants and rhinos in Africa."

Lund said the agency hopes the case will create a "deterrent for other would-be smugglers tempted to engage in this activity."

Part of Zheng's plea agreement would forbid him from buying, selling or trading any endangered species items regardless of their permit status.

Webb said Zheng maintains a passion for dealing other antiquities — he has run an online business called Crouching Dragon Antiques from home since 2010 — and has written books on the subject.

Adam Hammer, a university spokesman, said Zheng is still employed at St. Cloud State, which is "following due process" pending the outcome of the case, per the university's employment agreement.

Zheng will be sentenced May 9 in U.S. District Court in Minneapolis. He faces up to 10 years in prison and a $500,000 fine.

Stephen Montemayor • 612-673-1755

Twitter: @smontemayor