KANSAS CITY, Mo. – A Las Vegas-based company and its owners have agreed to plead guilty in connection with tainted pet food in 2007 that may have killed thousands of dogs and cats, according to a court document.

An attorney for Stephen S. Miller, co-owner of ChemNutra Inc., said his client had reached a plea agreement with prosecutors and would plead guilty plea at a hearing June 16, according to the papers filed in court last week.

Miller's wife, Sally Miller, and ChemNutra also plan to plead guilty, the filing said. Attorneys did not immediately respond to calls seeking comment Tuesday.

Don Ledford, a spokesman for the U.S. Attorney's office, said the office couldn't discuss any plea agreement until it had been approved by a judge.

The Millers and ChemNutra, along with two Chinese companies, were indicted in February 2008 on charges alleging they imported wheat gluten tainted with the chemical melamine, which was then sold to pet food makers. Thousands of cats and dogs reportedly sickened or died after eating the tainted food.

ChemNutra and the Millers were charged with 13 misdemeanor counts of introduction of adulterated food into interstate commerce, 13 misdemeanor counts of introduction of misbranded food into interstate commerce and one felony count of conspiracy to commit wire fraud.

Xuzhou Anying Biologic Technology Development Co. and Suzhou Textiles, Silk, Light Industrial Products Arts and Crafts I/E Co. were also indicted.

The indictments alleged that Suzhou Textiles, an export broker, mislabeled 800 metric tons of tainted wheat gluten manufactured by Xuzhou to avoid inspection in China. Suzhou then did not properly declare the contaminated product it shipped to the U.S. as a material to be used in food, the indictment said.

According to the indictment, ChemNutra picked up the melamine-tainted product at a port of entry in Kansas City, then sold it to makers of various brands of pet foods. The indictment alleges that Xuzhou added the melamine to artificially boost the protein content of the gluten to meet the requirements specified in Suzhou's contract with ChemNutra.

Prosecutors said adding the melamine, which would allow it to pass chemical inspections for protein content, was cheaper than actually adding protein to the gluten.

They added at the time that prosecutors weren't alleging that the Millers and ChemNutra knew that the product was toxic, only that they were aware the product had been shipped into the U.S. under false pretenses and failed to notify their customers.