Christina A. Flocken, 59, of Longwood, Fla., entered a guilty plea Monday in U.S. District Court. Under an agreement with federal prosecutors, she pleaded guilty to conspiracy to defraud the federal government and to harboring illegal aliens, said Hagen W. Frank, an assistant U.S. attorney.

Flocken could be sentenced to up to five years in prison and ordered to pay a $250,000 fine plus a share of a restitution judgment exceeding $15 million, Frank said.

The government's investigation into Rosenbaum-Cunningham International Inc., or RCI, a Florida-based cleaning contractor, led to the nationwide arrests in February of more than 200 illegal immigrants, mostly Mexican nationals.

Owners Richard M. Rosenbaum, 61, and Edward S. Cunningham, 44, pleaded guilty to identical charges under plea agreements with federal prosecutors. Cunningham, of West Palm Beach, Fla., entered his plea Friday. Rosenbaum, of Longwood, Fla., entered his plea Oct. 17.

Rosenbaum's sentencing hearing was set for Feb. 4. Sentencing hearings for Cunningham and Flocken were not scheduled as of Monday, Frank said.

Rosenbaum faces up to 10 years in prison and a $500,000 fine. Cunningham faces a 5-year prison term and up to $250,000 in fines. Both also will have to pay a share of the restitution judgment.

The investigation began at Grand Traverse Resort and Spa in Acme, in Michigan's northwestern Lower Peninsula.

The practice of paying cash wages to workers deprived the U.S. government of about $18.6 million in employment taxes, according to the indictment against the three. The government said RCI contracted with the resort between June 1997 and March 2006.

A telephone message seeking comment on Flocken's plea was left Monday at Grand Traverse Resort.