Two members of an immigrant family that owns a Bellingham engine manufacturer pleaded guilty Tuesday to “knowingly hiring illegal immigrants” in what the local United States Attorney’s office is calling its first successful criminal prosecution of an employer on such charges.

Shafique Amirali Dhanani, 46, and his sister, Shirin Dhanani Makalai, 52 — immigrants who fled Uganda in the 1970s — pleaded guilty to felony charges, admitting they knew some of the 28 workers arrested at Yamato Engine Specialists in February had used false names and Social Security numbers on federal employment forms when they were hired.

Under the plea agreement, the two most likely face probation.

The first work-site raid of the Obama administration, the Bellingham case gained national attention when Homeland Security Secretary Janet Napolitano ordered a probe into the actions of local agents who conducted it.

Her Department of Homeland Security has since issued guidelines on how such raids should be carried out, saying it wants investigations to focus more on employers who hire illegal immigrants than on the immigrant workers themselves.

“This case should put employers on notice that if they knowingly employ those who lack legal status, they face prosecution for federal felonies,” United States Attorney Jeffrey C. Sullivan said in a statement.

Dhanani and Makalai sat solemnly through the court proceedings. In a statement, they said, “We very much regret violating the law and dishonoring the fine reputation Yamato Engines and our family enjoys. ... ”

The company itself, which manufacturers Japanese car engines and transmissions, faces fines of up to $500,000 on criminal charges that it “encouraged and induced” illegal immigrants to live in the U.S. between 2006 and 2009. A court hearing on the charge was delayed.

In February, U.S. Immigration and Customs Enforcement officers arrested the 28 immigrants at the plant — more than one-quarter of the company’s work force. The employees, from Mexico and across Central America, all admitted to being in the country illegally.

In the weeks that followed, most were released; one was deported. Some posted bond; many others got a deal from the government in which they were freed without bail, granted work permits and signed a form acknowledging that deportation action against them was being deferred while the investigation of their employer proceeded.

Across the country, Napolitano delayed raids planned for other work sites while she reviewed agency policy. In the end, her review of the Bellingham raid became part of a revised set of guidelines her department issued, directing ICE agents to focus work-site investigations on prosecution of employers.

The Dhanani family fled Uganda for Canada in 1971, when dictator Idi Amin Dada led a violent coup and slaughtered hundreds of thousands of people. They opened their engine plant in Bellingham 20 years ago. At the time of the raid, Makalai had said the owners had been cooperating with ICE and thought they were on a track to correct any problems.