The criminal case against an American company responsible for importing contaminated pet-food ingredients that sickened and killed thousands of family pets in 2007 ended Friday with the sentencing of ChemNutra, Inc., and its owners, Sally Qing Miller, 43, and Stephen S. Miller, 57, of Las Vegas.

The Millers, a married couple, each was fined $5,000 and given three years probation in U.S. District Court in Kansas City, Mo., by U.S. Magistrate Judge John T. Maughmer. In addition, ChemNutra was fined $25,000.

The Millers and ChemNutra pleaded guilty last June to one count each of distributing adulterated food and selling misbranded food, both Class A misdemeanors. They did not admit to knowingly distributing and selling the contaminated food.

A press release from the U.S. Attorney’s Office at the time stated that the Millers could be sentenced to up to two years in prison without the possibility of parole, and that they and the company together could be fined up to $800,000 and ordered to pay restitution. However, prosecutors recommended a total of $35,000 in fines and three years of probation for each of the individuals. The judge followed the recommendation.

The court opted not to impose restitution, citing a $24-million settlement in a related class-action civil suit handled by the U.S. District Court for the District of New Jersey.

In the civil case, ChemNutra is one of more than two dozen defendants contributing to a $24-million fund established to compensate people whose animals were affected by the tainted food. How much of the settlement fund was provided by ChemNutra — or any one of the other defendants in that case — is a secret.

Mary Elizabeth Gately, a lawyer for the defendants, told the VIN News Service: “That’s confidential information that’s not ever been released.”

Gately also said she could not comment on how the distribution was decided — whether based upon market share, ability to pay, in equal shares or by some other formula.

The settlement was approved in November 2008 but disbursements from the fund have yet to be made, pending two separate appeals to the settlement. Oral arguments are scheduled for both appeals on Feb. 22.

The contamination came to light in March 2007 as the U.S. Food and Drug Administration (FDA) fielded thousands of reports of sick and dying cats and dogs that had eaten certain pet foods. The FDA received more than 14,000 consumer complaints within a month, amounting to more than twice the number of complaints it typically receives in a year for all products the agency regulates, according to an account by the U.S. Attorney’s Office.

Investigators traced the problem to melamine, a nitrogen-rich chemical used in fertilizer and plastics manufacturing. Unscrupulous suppliers in China added melamine to wheat gluten, a protein source, to boost the product’s protein measurements. Together with cyanuric acid, a byproduct of melamine production, the contaminants formed crystals in the kidneys of the animals that ate the tainted food, causing renal disease and renal failure.

The poisoned product was imported by ChemNutra and the Millers into the United States and purchased by Menu Foods, a pet-food manufacturer based in Canada contracted by numerous companies to produce both private-label and name-brand wet pet foods. By the time authorities identified the source of contamination, many of the biggest names in pet food were involved, among them Hill’s Pet Nutrition, Mars, Inc., Nestle Purina PetCare Co., Royal Canin, The Iams Co. and Procter & Gamble.

Retail giants including Walmart, Target, Petsmart, Petco and Costco also were ensnared by the scandal, which spurred a recall involving more than 150 brands of pet food.

The Veterinary Information Network, which surveyed its members and tracked cases, estimates that 30,000 to 50,000 animals were affected. About 1,950 cats and 2,200 dogs died, by the reckoning of the U.S. Attorney’s Office, based on consumer reports received by the FDA.

In addition to ChemNutra and the Millers, two Chinese companies and their leaders — Xuzhou Anying Biologic Technology Development Co., Ltd., and Mao Linzhun; and Suzhou Textiles, Silk, Light Industrial Products, Arts and Crafts I/E Co., Ltd. and Chen Zhen Hao — were indicted in the United States. However, federal prosecutors are unable to bring them to court because this country does not have an extradiction treaty with China.

The pet food contamination turned out to be just the first chapter in an international saga involving melamine in food. In 2008, Chinese milk suppliers were found to have spiked milk products with melamine, again to boost the apparent protein content. Tainted milk powder wound up in baby formula, resulting in the deaths of at least six Chinese infants and sickening hundreds of thousands more.

According to a report by the BBC, a cattle farmer and a milk trader were sentenced to death for their roles in that poisoning scheme. The head of Sanlu Group, a large producer of baby milk powder, was sentenced to prison for life.