A Waterville woman who managed a Chinese restaurant in Brewer was sentenced Tuesday to 15 months in federal prison on immigration, money laundering and tax fraud charges.

Mei Ya Zhang, 29, was the fourth person to be sentenced as the result of a federal investigation that culminated in raids at several Chinese restaurants in Maine in 2011.

Federal and local investigators said Zhang’s uncle and aunt, Zi Qian Zhang and his wife, Ai Hui Lu, for whom Zhang worked, hid undocumented workers in squalid living conditions and then drove them to the restaurants to work long hours.

The elder Zhang and Lu owned about a dozen restaurants in Maine and other New England states, federal officials said at the time of the raids. Another niece, Mei Juan Zhang, 31, of Fairfield, was sentenced to a 14-month prison term on similar charges involving two Waterville restaurants in March and is an inmate at a federal prison in Danbury, Connecticut.

According to court records, between 2006 and 2011, Mei Ya Zhang was the manager of the Twin Super Buffet in Brewer, where she brought undocumented workers into Maine, had them work six days a week for eight to 10.5 hours per day.

The investigation said she hid about $400,000 in wages paid to the workers and “thwarted the collection of about $88,000 in employment taxes.”

Zhang was also ordered by U.S. District Judge John Woodcock to pay more than $88,000 in restitution to the Internal Revenue Service and to serve three years of supervised release following her prison sentence.

Zhang pleaded guilty June 5, 2013, to harboring undocumented immigrants for commercial advantage and private financial gain, money laundering conspiracy, and conspiracy to file false employer’s federal tax returns..