BANGOR — One of the country’s most sophisticated marriage fraud schemes officially ended Tuesday when a federal judge sentenced the last defendant to a year in prison.

Margaret Kimani, 30, of Worcester, Mass., was one of 28 defendants convicted in Maine of being part of a scam that paid American citizens living in Maine to wed African immigrants so they could more easily obtain permanent residency status, known as a green card, and achieve citizenship more easily, Maine’s U.S. Attorney Thomas E. Delahanty II said at a press conference after the sentencing.

“America’s legal immigration system is not for sale and we will move aggressively against those who willfully compromise the integrity of that system simply to enrich themselves,” said Bruce Foucart, special agent in charge for U.S. Immigration and Customs Enforcement’s Homeland Security Investigations in Boston, whose office headed the investigation that led to the prosecutions.

“HSI’s message is very simple,” he said at the press conference. “U.S. citizenship is not for sale and there are consequences for those who commit marriage fraud. If you commit marriage fraud, there isn’t going to be a honeymoon.”

The investigation was launched in 2005 and identified more than 40 sham marriages in the Lewiston/Auburn and Newport areas between U.S. citizens in Maine and nationals from Kenya, Uganda, Zambia and Cameroon. Prosecutions began in 2010.

The scheme was hatched by Rashid Kakande, 41, of Lexington, Mass., and James Mbugua, 53, of Springfield, Mass., according to court documents. The men had family connections in Lewiston. They recruited sisters Angela Roy, 40, of Sabattus and Torri Roy Patterson, 36, of Lewiston, who recruited other Mainers to marry foreign nationals, most of whom lived in Massachusetts, according to Foucart.

Immigrants seeking an American spouse would pay Kakande or Mbugua between $1,000 and $1,500, Foucart said Tuesday. Out of that fee, the men would pay the sisters and the spouses. Kimani’s husband was paid $500 to marry her. Spouses who provided false information, such as joint bank accounts, rent receipts and utility bills to show that the couple was living together, and attended interviews with immigration officials received further payments.

Assistant U.S. Attorney Gail Malone, who prosecuted all of the cases, said at the press conference that Kakande and Mbugua targeted Maine because there is no waiting period for marriage in the state as there is in New Hampshire and Massachusetts. She said that although the investigation spanned Massachusetts, New Hampshire, Vermont and Maine, the only prosecutions were in Maine and no cases are pending in other states.

Kimani and three other defendants were the first in the nation prosecuted for filing false claims of spousal abuse with U.S. immigration authorities in violation of the Violence Against Women Act, Delahanty said. The act allows immigrants, who are subject to abuse, to apply for permanent residence without the knowledge or consent of their U.S. spouse.

Foucart said that eight of the 18 foreign nationals convicted have been deported. He said that three others are considered to be fugitives. Foucart said that removal proceedings are pending against the rest.

Sentences in the case ranged from probation to the two years in prison ringleader Kakande originally was sentenced to in June 2011. In April 2012, his sentence was amended to 19 months, after he testified against another defendant, Malone said Tuesday.

Kakande, who is a U.S. citizen, also was ordered to pay a $20,000 fine, the amount the judge estimated he made arranging sham marriages. He was released in August 2012, according to the U.S. Bureau of Prisons’ Inmate Locator website.

Mbugua, who arranged Kimani’s marriage, disappeared in 2010 before he could be tried and is listed as a fugitive on the court’s electronic case filing system.

In addition to prison time, U.S. District Judge John Woodcock sentenced Kimani in U.S. District Court to three years of supervised release. Kimani, who is a licensed practical nurse and has a daughter who is a U.S. citizen, is expected to be deported.

Kimani married a Maine man in Lewiston on Dec. 30, 2003, nearly two years after her visitor’s visa expired Feb. 3, 2002, in order to gain U.S. citizenship more easily, according to court documents.

She was indicted by a federal grand jury in August 2012 but was not arrested until 13 months later when she returned from a visit to her native Kenya. She has been held without bail since her arrest Sept. 5, 2013, at JFK International Airport in New York City. A jury found her guilty of one count of conspiracy to defraud the U.S. in December.

Kimani was awarded lawful permanent residency in March 2010 based on the false information that her husband sexually, physically and emotionally abuse her, according to the prosecutor.

She faced up to five years in prison and a $250,000 fine. Under the prevailing federal sentencing guidelines, she faced six to 12 months in prison. The time that she has been held will be credited to her sentence.

Defendants and ties to Twin Cities

* Margaret Kimani, 30, of Worcester, Mass.; from Kenya; convicted of conspiracy to defraud the United States; sentenced to one year in prison plus one year of supervised release; married in Lewiston on Dec. 30, 2003 to a Maine resident, who was paid.

* Emmanuel Musiitwa of Woburn, Mass.; from Uganda; born 1952; pleaded guilty to one count of conspiracy to defraud the United States; sentenced to four months in prison, plus one year of supervised release; married in Waltham, Mass., on Aug. 9, 2002, to a Lewiston woman, who was paid.

* Grace Nyaga of Lowell, Mass.; from Kenya; born 1981; pleaded guilty to one count of conspiracy to defraud the United States; sentenced to three months in prison; married at Auburn City Hall on April 5, 2004, to an Auburn man, who was paid.

* Jecinta Wambui Ngige of Attleboro, Mass.; from Kenya; born 1975; convicted on a charge of conspiracy to defraud the United States; sentenced to four months in prison plus one year of supervised release; married at Lewiston City Hall on Jan. 30, 2004, to Lewiston man who was paid.

* Rashid Kakande of Woburn, Mass.; born 1972; convicted of one count of conspiracy to defraud the United States; sentenced to 19 months in prison plus three years of supervised release; arranged for four paid marriages in Lewiston and for three paid marriages in Auburn to local residents from 2003 to 2005.

* Angela Roy of Lewiston; born in 1973; pleaded guilty to one count of conspiracy to commit marriage fraud; sentenced to 10 months in prison plus three years of supervised release; arranged, caused to happen or participated in at least 15 marriages for pay between foreign nationals from Kenya and Uganda and Maine residents between 2003 and 2006.

* Torri Roy Patterson of Auburn; born in 1977; pleaded guilty to one count of conspiracy to commit marriage fraud; sentenced to six months in prison and $5,000 fine, plus three years of supervised release; arranged, caused to happen or participated in at least five marriages for pay between foreign nationals from Kenya and Uganda and Maine residents between 2003 and 2006.

* Catherine Nantume of Woburn, Mass.; from Uganda; born 1978; convicted on one count of conspiracy to defraud the United States; sentenced to one year in prison, plus three years in supervised release followed by deportation; married at Auburn City Hall in Aug. 19, 2002, to Auburn man, who was paid.

* Joseph Kasirye of Framingham, Mass.; from Uganda; born 1978; convicted on one count of conspiracy to defraud the United States; sentenced to time served in prison; married on Dec. 5, 2003, to Torri Roy Patterson of Auburn, who was paid.

* Thomas Taylor of Mechanic Falls; born 1964; pleaded guilty to one county of conspiracy to defraud the United States; sentenced to six months in prison and a $4,500 fine plus three years of supervised release; married for payment in Newport on Feb. 22, 2005, to a Kenyan national.

* Henry Swan of Lewiston; born 1974; pleaded guilty to one count of conspiracy to defraud the United States; sentenced to four months in prison and $6,000 fine plus three years in supervised release; married for payment on March 3, 2003, in Auburn to a Zambian national and participated in two other “sham” marriages.

* Heather Dugas of Lewiston (no birth year provided); pleaded guilty to one county of conspiracy to defraud the United States; sentenced to three months in prison and $4,000 fine plus two years of supervised release; married for payment a Kenyan national on April 28, 2003, in Auburn.

* Paula German of Auburn; born 1974; pleaded guilty to one count of conspiracy to commit marriage fraud; sentenced to three months in prison and a $2,000 fine plus three years of supervised release; arranged, caused to happen or participated in at least four “sham” marriages for money between 2003 and 2006 involving Kenyan or Ugandan nationals and was married to James Muhoro, a Kenyan national, on Dec. 29, 2003.

* Samuel Paradis of Auburn; born 1985; pleaded guilty to one count of conspiracy to defraud the United States; sentenced to three months in prison and a $2,500 fine plus three years of supervised release; married for payment on Oct. 6, 2004, in Lewiston to a Kenyan national. In 2005, served as witness for two other “sham” marriages.

* James Muhoro of Dracut, Mass.; from Kenya; born 1974; pleaded guilty to one count of conspiracy to defraud the United States; sentenced to two months in prison; married on Dec. 29, 2003, to Paula German of Auburn, who was paid.

* Janet Wanjiru Thumi of Euless, Texas; from Kenya; born 1971; pleaded guilty to one count of conspiracy to defraud the United States; sentenced to two months in prison; married on Oct. 6, 2004, in Lewiston to Samuel Paradis of Auburn, who was paid.

* Edward Kizito of Waltham, Mass.; from Uganda; born 1956; pleaded guilty to conspiracy to defraud the United States; sentenced to one month in prison and one year of supervised release; married on Dec. 4, 2003, at Lewiston City Hall to a Maine resident, who was paid.

* Beth Stewart of Lewiston; born 1981; convicted of one count of conspiracy to defraud the United States; sentenced to three years of probation and a $500 fine; unsuccessfully appealed; married for payment in Auburn on March 29, 2005, to a Kenyan national.