As punishment for bits of metal ending up in Children's Tylenol and other medicines, Johnson & Johnson pleaded guilty Tuesday to one criminal count in federal court in Philadelphia and will pay $25 million for poor manufacturing practices at its Fort Washington plant.

The plea relates to metal particles, such as nickel and chromium, that were found in children's liquid medicine made at the McNeil Consumer Healthcare plant in Montgomery County between May 2009 and April 2010. The fine is based on a percentage of the sales of those products during the 11 months included in the plea.

"McNeil's failure to comply with current good manufacturing practices is seriously troubling," acting Assistant Attorney General Benjamin C. Mizer said in a statement.

In early May 2009, a customer complained to McNeil about the presence of "black specks in the liquid on the bottom of the bottle" of Infants' Tylenol, according to the plea agreement and documents filed in Philadelphia by prosecutors, including Assistant U.S. Attorney Mary Beth Leahy and Jeffrey Steger, of the Justice Department's consumer protection branch. The customer returned the bottle to McNeil, and the company found a mix of nickel and chromium in the remaining liquid.

By April 2010, McNeil had found 30 batches of over-the-counter liquid medicine, including Infants' Tylenol, Children's Tylenol, and Children's Motrin, that contained some or all of the metal particles.

The problem was eventually traced to a machine part made from Waukesha 88, "a composite metal that is mostly nickel, but also includes tin, iron, bismuth and chromium."

The company reported no injuries from the episode.

By law, McNeil was required to have a written plan to document and correct the specific problem along with a systematic evaluation to prevent future occurrences. When a Food and Drug Administration inspector asked for that document, a McNeil employee confirmed that McNeil had no such plan, according to the plea agreement.

It wasn't until April 13, 2010 - five days after its last discovery of problem liquids - that McNeil halted production on one line. On April 30, in conjunction with the FDA, it issued a recall notice. Besides the infants' and children's Tylenol and Motrin that were discussed in the criminal plea, McNeil recalled Zyrtec and Benadryl products made at the facility.

Tuesday's plea ended the criminal phase of a two-part process. J&J said initially it would spend $100 million on repairs to the McNeil facility for future use. But before it can resume production in Fort Washington, it must satisfy the FDA that it has fixed its problems outlined in a federal consent decree. Judge Ronald L. Buckwalter, who presided Tuesday, must sign off on that, too.

McNeil plants in Lancaster and Puerto Rico did not have to shut down, but operated under much tighter limits. Though J&J shifted production to other plants worldwide, iconic products were absent from U.S. shelves for several years, the company has said.

"McNeil has been implementing enhanced quality and oversight standards across its entire business to ensure we are best able to meet our commitment to consumers, patients and doctors who rely on our products," said Carol Goodrich, a company spokeswoman.