PORTLAND – A former bookkeeper for a Kittery health club alleged to be a brothel has pleaded guilty to conspiracy to launder more than $3 million for the club.

Mary Ann Manzoli, 64, of Lynnfield, Mass., is the widow of one of the former owners of the Kittery Health Club, also known as the Danish Health Club.

She pleaded guilty in U.S. District Court on Jan. 10 and now faces up to 10 years in prison and a $250,000 fine. A sentencing date has not been scheduled.

Federal authorities allege that the club, which advertised itself as a massage parlor, served for 20 years as a place where male customers paid to have sex with women.

Court documents say Manzoli regularly wrote paychecks for the club’s managers and paid bills for utilities, laundry and heating oil. She also authorized payments for advertisements in the adult entertainment section of the Boston Phoenix, and other magazines distributed in strip clubs and adult bookstores, court records show.

Prosecutors say that beginning in 1996, Manzoli became more involved in K&D Realty Trust, which held assets and proceeds produced by the club.

“In the later part of 2001, Manzoli became the sole beneficiary of K&D Realty Trust,” Assistant U.S. Attorney Toby Dilworth wrote in court records. “She transferred millions of dollars of proceeds from the club into K&D Realty Trust and other accounts she controlled.”

Transfers from the club’s account into those accounts totaled $3,021,426, according to court records.

Manzoli is the third person to be charged in connection with the federal investigation into the Kittery Health Club.

Kittery lawyer Gary Reiner was charged last month with money laundering and violation of interstate prostitution laws. He has pleaded innocent.

Russell Pallas, who was a former manager of the club, pleaded guilty to prostitution charges on Dec. 15 and is awaiting sentencing.