U.S. District Judge Cecilia Altonaga is expected Friday to sentence members of a network who sold false Cuban birth certificates to undocumented immigrants so they could pretend to be Cubans and obtain green cards.

Thanks to the 1966 Cuban Adjustment Act, Cubans who arrive in the United States without a visa can remain in the country and apply for residence after a year and one day. This immigration benefit is available only to people who can prove they are Cuban citizens.

The case in Miami federal court exposed the first public details of what has become an increasingly common practice in South Florida.

Miami immigration attorney Wilfredo Allen said he has represented more than a half-dozen clients in the past few years who have been accused by immigration authorities of carrying residence cards obtained illegally with false Cuban documents.

Allen said immigration authorities have developed sophisticated methods to discover the fraud related to the Cuban Adjustment Act, and can verify, if they have any suspicion, whether the applicant is presenting an authentic Cuban document.

The network, consisting of four members, three from Naples and one from Kissimmee, was dismantled in September, when Immigration and Customs Enforcement agents arrested and charged them with conspiring to commit immigration fraud.

All initially pleaded not guilty, but changed their minds and their pleas. Since then, Judge Altonaga has sentenced one of them to six months in prison and two years of parole, including nine months of house arrest.

Two more are scheduled to be sentenced Thursday.

The accused are Nelson Daniel Silvestri Soutto, Laura María Ponce Santos and Amelia Osorio of Naples, and Fidel Morejón Vega of Kissimmee.

People familiar with the case said Morejón and Osorio are Cubans and Silvestri and Ponce are Uruguayans. Their clients were of various nationalities, including Argentineans, Colombians, Costa Ricans, Mexicans, Peruvians, Salvadorans and Venezuelans.

None of the defense attorneys or immigration authorities would comment Wednesday.

Documents available in court pointed to Morejón as the presumptive leader of the group.

He was charged with selling Cuban birth certificate at prices ranging from $10,000 to $15,000 each while posing as a high-ranking immigration official when meeting with potential clients. One was an undercover agent who posed as a Mexican.

For 3 ½ years, beginning in 2009, at least 50 undocumented immigrants bought false birth certificates, according to court documents. Some of them became residents, including some of the accused who then acted as recruiters for Morejón, the court documents state.

The scam netted more than half a million dollars, according to a memorandum in the case.

Other court documents indicate that Morejón may have obtained the birth certificates in Cuba. They don’t specify whether Morejón obtained the certificates at a Cuban government office or received them from a corrupt official who printed them himself.

One of the network’s clients, identified in court records only as J.R., cooperated with investigators and introduced Morejón to an undercover agent who wanted to buy a Cuban birth certificate.

The court documents include transcripts of some of the conversations between Morejón, J.R. and the undercover agent, identified as Rolando.

In one of the transcripts, Morejón said that for the fraud to be successful, Rolando and J.R. would be taken to the Florida Keys and left there as newly arrived rafters. Morejón told them that when the immigration officials picked them up they had to say they were Cubans and know the details of their birth certificates by heart.

In the conversation taped surreptitiously, Morejón advised them on how to respond to questions, but J.R. stumbled when he tried to remember where he was born in Cuba.

“So, if they ask you, ‘Where were you born?’ at that moment you have the birth certificate. ‘Where were you born?’ asks Morejón in the transcription.

“I was born in Havana . . . no, in Guinness, Guinness, Cuba,” responds J.R, referring to the city of Güines, 25 miles southeast of Havana.

Morejón also advised J.R. not to talk too much while in the custody of immigration authorities before being paroled, apparently to avoid detection of their non-Cuban accents or saying things that a Cuban could not say or know.

“You’re going to be at a place where there would be seven or eight people,” Morejón tells J.R., according to the transcript. “ ‘Hey, how did you get here?’ ‘In a raft.’ ‘Are you Cuban?’ ‘Yes.’ That’s all. That’s all. You don’t have to say more or make much conversation.”