The U.S. Department of Justice announced on Friday the latest in a yearlong series of investigations and hearings: Two former Japanese auto executives have pleaded guilty and agreed to prison time for dishonest pricing of parts used by Ford Motor Co. (NYSE:F); Toyota Motor Corp. (TYO:7203); and Fuji Heavy Industries (TYO:7270), the company that owns the Subaru brand.

Shigehiko Ikenaga and Tatsuo Ikenaga, the former president and vice president of Osaka-based Diamond Electric Mfg. Co. Ltd., admitted to participating in a global conspiracy to fix the price of the ignition coils used in vehicles made in the U.S. and elsewhere, the U.S. DOJ announced on Friday.

Shigehiko, the president of Diamond Electric at the time the antitrust crimes took place between July 2003 and February 2010, agreed to serve 16 months in a U.S. prison. Tatsuo, who was promoted to Diamond Electric’s vice president position in 2008, and who also served as the company’s president of U.S. operations based in Eleanor, W. Va., agreed to serve 13 month in U.S. prison. Each has agreed to pay $5,000 and to cooperate with authorities in the ongoing investigation.

In September, Diamond Electric pleaded guilty for its participation and paid a $19 criminal penalty. Diamond Electric and co-conspirators at other parts suppliers held meetings and conducted communications to coordinate bids sent to auto manufacturers, in violation of the Sherman Act, which carries a maximum penalty of a decade in prison and a criminal penalty up to $1 million per individual.

“The division’s ongoing investigation has resulted in more than two-dozen executives serving prison time for their participation in illegal, auto parts conspiracies,” Brent Snyder, U.S. deputy dssistant attorney general for the antitrust division’s criminal enforcement program, announced in a statement Friday afternoon.

So far 28 people and 24 companies have been charged in the U.S. government’s ongoing investigation into bid-rigging that artificially inflated the price of parts to manufacturers.