A Las Vegas food import company, two Chinese businesses and the companies' top executives were indicted yesterday by a federal grand jury for their parts in a tainted pet food scandal last year that sickened or killed thousands of dogs and cats, the Justice Department said.

The announcement by John F. Wood, U.S. Attorney for the Western District of Missouri, marks the first time a domestic company has faced criminal charges because melamine - a chemical found in plastics that can cause kidney failure in animals - was added to shipments of wheat gluten, a binding agent used in pet foods.

The pet food contamination crisis, which prompted the recall of more than 60 million containers of dog and cat food, was the first in a wave of product scares that alarmed Americans about the quality of goods made in China.

Melamine can artificially inflate the protein content of food additives, allowing exporters to use cheaper ingredients, the indictment said.

"In today's global economy, crimes that occur halfway around the world can seriously impact our lives," Wood said. "Millions of pet owners remember the anxiety of last year's pet food recall. These indictments are the product of an investigation that began in the wake of that recall."

ChemNutra Inc., which imports Chinese food and ingredients for distribution across the United States, along with its owners, Sally Qing Miller, 41, and her husband, Stephen S. Miller, 55, were charged in a 27-count indictment with evading mandatory inspections of the ingredients in China, delivering adulterated food, misbranding food and conspiring to defraud the companies that unknowingly bought the tainted ingredient.

"ChemNutra and Steve and Sally Miller deny in the strongest of terms the allegations by the Department of Justice and look forward to the opportunity to prove their innocence at trial," the company said in a statement. "Neither Mr. nor Mrs. Miller had any intent to defraud or any knowledge of wrongdoing."

Wood said the felony count against ChemNutra and the Millers alleged that they knew the Chinese exporters had put an incorrect product code on the exports, allowing the shipment to leave China without the normal inspections of food, and didn't disclose that fact to their customers.

"We don't allege there that they knew that the wheat gluten was adulterated with the melamine," Wood said in an interview. "But to convict, we don't have to show that they knew. ... You are responsible for the content of the food ingredients that you're selling and therefore can be charged with the misdemeanor if you distribute adulterated or misbranded food, regardless of whether you knew if it was adulterated or misbranded."

In a separate case, the grand jury returned a 26-count felony indictment against two Chinese companies and their top executives, accusing them of intent to defraud and mislead, delivering adulterated foods and falsely labeling wheat gluten to avoid export inspection.

Those charges name Xuzhou Anying Biologic Technology Development Co., a Chinese processor of plant proteins; Chinese owner Mao Linzhun, age unknown; Suzhou Textiles, Silk, Light Industrial Products, Arts and Crafts I/E Co., a Chinese export company; and its president, Chen Zhen Hao, 58, a Chinese national.

Abigail Goldman writes for the Los Angeles Times.