Over the years, people have come up with many desperate schemes to leave behind Casablanca.

One of the most recent involved a Moroccan man, Abdellatif Nouira, who told winners of the local green card lottery that he could help them breeze through a final background check if they would marry his siblings and bring them along to America, law enforcement officials say.

Today, eight years after the alleged scheme began, the trial of Mr. Nouira and two of his brothers, a sister, his ex-wife, and a consulate employee opens in U.S. District Court in Brooklyn.

The allegations against Mr. Nouira suggest that in Morocco he was able to broadly manipulate the green card process even though he had no official connection to it. The trial will focus on the alleged corruption and the defendants’ allegedly sham marriage certificates. But this drama involving a city known best among most Americans for the movie by the same name will also highlight the vulnerabilities of America’s green card system.

The case against Mr. Nouira began nearly two years ago, when the State Department began investigating why an unusual number of green cards had been going to Moroccans with common addresses and names since 1998, according to a court filing.

Each year, 3,000 applicants in Morocco become eligible to receive a green card through a lottery system. Following a background screening process, only about 2,000 of those winners are cleared, according to court filings. Those who are can also secure green cards for a spouse and children.

Mr. Nouira was a fixer, a man who contacted winners of the lottery and promised that he could help them through the screening process, according to the government court filings.The documents allege that he coached lottery winners on how to answer the questions that U.S. Embassy staff were likely to ask as part of the vetting process.

In fact, Mr. Nouira may have acted as much more than a consultant. One of the lottery winners he contacted said she was afraid that Mr. Nouira had the power to sabotage her application if she did not consent to marry one of his relatives, according to an investigator’s affidavit.

The indictment states that Mr. Nouira was in contact with a consular employee, Mustapha Hamdi, who was able to grant green cards to those whom Mr. Nouira sent his way. While Mr. Hamdi’s precise job at the consulate in Casablanca is not stated in court filings, the indictment said he had the authority to grant entrance to the consulate to visitors and did so as part of the alleged visa ring.

Mr. Nouira’s attorney, Barry Weinstein, declined to comment.

The criminal complaint suggests that Mr. Nouira’s main motive was to assist family members in gaining entry to America. The indictment makes no mention of payment and only states that Mr. Nouira compelled certain green card winners to marry four of his relatives. He secured a green card for himself through marriage, and flew to New York earlier this year.

Other court documents suggest that there were additional relatives of Mr. Nouira who entered America on green cards and that, in one case, $15,000 changed hands to pay for the preparation of false marriage certificates.

The status of the marriages that Mr. Nouira and his relatives entered into is unclear. Prosecutors have sought documents from the Moroccan government that show the marriages were never filed with the state and are therefore not valid. In several of the cases, investigators have secured the cooperation of the spouses to Mr. Nouira’s relatives, who corroborated details about the scheme, according to court filings.

The government has said it will call between 11 and 15 witnesses, including one from Morocco, where the case has attracted some attention from the press.The judge in the case, Jack Weinstein of U.S. District Court in Brooklyn, has allowed Mr. Nouira, who is confined to his home on $2 million bail, to attend a mosque in Astoria, Queens, twice a week and English-language classes five times a week.

Not even the coming trial has stopped Mr. Nouira’s endless scheming, the government alleges. In a letter filed two weeks ago with the court, the prosecutor on the case, Walter Norkin, said Mr. Nouira has been using his visits to a mosque and to a nearby café to try to meet with potential witnesses.