DALLAS— The president of Shipley Do-Nuts and the family-owned company pleaded guilty to federal charges Thursday in one of the latest cases against employers accused of hiring illegal immigrants.

Lawrence W. Shipley III pleaded guilty in Houston to a misdemeanor charge of continuing to employ unauthorized workers and was placed on probation.

Shipley Do-Nuts pleaded guilty to a felony charge of knowingly hiring illegal immigrants and must forfeit $1.3 million.

The company also was placed on probation, officials said.

Shipley has been president of the doughnut maker since 2005 and is the grandson of the company’s founder.

Agents with U.S. Immigration and Customs Enforcement raided Shipley's Houston headquarters and plant in April. They arrested more than a dozen illegal immigrants, including some who lived in a dormitory for workers.

Shipley Do-Nuts has more than 190 stores in Alabama, Arkansas, Louisiana, Mississippi, Tennessee, and Texas.

The case is but the latest to be brought against employers and managers who hire illegal immigrants recently.

Many are the result of lengthy investigations, according to Julie Myers, assistant secretary of homeland security.

“We’re actually seeing those cases come to fruition,” she said, adding that the investigations often involve poring over volumes of documents.

“Sometimes it takes months. Sometimes it takes several years, that’s not uncommon,” she said.