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After four years of unrelenting investigations, former U.S. Rep. David Rivera's fate in a criminal campaign finance probe could rest squarely on the shoulders of a woman who was his close friend and longtime Republican political consultant with deep roots in South Florida's Cuban exile community.

Ana Alliegro, 44, is in a Broward County jail awaiting an Aug. 25 trial on four felony campaign finance charges that each carry maximum five-year prison sentences. She has pleaded not guilty and was denied bail by two separate judges because, in the midst of the FBI investigation, she twice fled to Nicaragua rather than meet with prosecutors and agents.

Alliegro is charged with funneling about $80,000 to an unknown Democratic congressional candidate, Justin Lamar Sternad, who was running in the 2012 primary for the chance to challenge GOP incumbent Rivera in Florida's 26th congressional district. Prosecutors say Sternad, a low-paid Miami Beach hotel clerk with no political experience, was a ringer candidate intended to smear Democrat Joe Garcia, who is much better known and ultimately toppled Rivera in the general election.

Sternad pleaded guilty, has cooperated with the investigation and on July 10 was sentenced to seven months in federal prison. Although prosecutors have not identified Rivera by name, they refer to Alliegro as working with "co-conspirator A." Sternad directly implicated Rivera in testimony, and defense lawyers say Rivera is the person prosecutors are referring to.

"I hate to admit that I let Ana Alliegro and David Rivera take advantage of me," he said in court the day he was sentenced.

Rivera, once a rising GOP star in Florida and close friend of U.S. Sen. Marco Rubio when both were state legislators, has not been charged and again denied any involvement or wrongdoing in an email to The Associated Press.

"The answer is the same one I gave you two years ago: No," he wrote.

Rivera in May filed papers to run again for his old U.S. House seat but suspended his campaign in July, citing confusion about congressional districts when a judge invalidated Florida's new map. But he seemed to struggle before that to gain traction in the race, reporting only $11,000 in campaign contributions for the three-month period ending July 15 — and that was a loan from Rivera to his own campaign.

Alliegro was Rivera's close political ally, both of them steeped in the Cuban-American community fiercely opposed to communist Cuba. Her grandfather, Anselmo Alliegro, held a number of senior government and legislative posts under former Cuban President Fulgencio Batista and was even president for a day in 1959 after Batista fled Fidel Castro's revolution.

Former federal prosecutor David S. Weinstein said it appears that without Alliegro's cooperation it will be difficult to build a winnable case against Rivera. Alliegro's lawyers have filed several motions seeking to have several pieces of evidence thrown out, hardly a sign of cooperation.

"If Alliegro loses her pending motions, her only choice will be to sign a cooperation agreement, flip on Rivera and reduce her (prison) time," Weinstein said. "Otherwise, she is going to be looking at a lengthy prison sentence as her reward for keeping her mouth shut."

Yet, Alliegro might be a problematic witness.

Assistant U.S. Attorney Thomas Mulvihill said Alliegro in fall 2013 signed a document indicating she would plead guilty. But instead of following through — and even though she had surrendered her passport — Alliegro flew to Texas, boarded a bus for Mexico and took a plane to Nicaragua, where she opened a hair salon in the tourist town of Granada. It turned out she had a duplicate passport.

According to court documents, Alliegro had different versions of a false resume on her computer seized by FBI agents, one claiming she had received a received a political science degree from Harvard University and the other claiming she attended St. Thomas University near Miami.

"Integrity may not be Alliegro's strongest character trait," Mulvihill said in court papers.

She's had other brushes with the law. In 2007, she was charged with firing a gun into the ceiling at the home of her ex-husband, a developer with whom she wanted to restart a relationship, according to court records. A police report said she sat on a desk naked and compared the gun to the male sexual organ. She eventually pleaded guilty to reduced charges and was sentenced to probation.

Ultimately, Alliegro was detained by Nicaraguan police in March, turned over to U.S. authorities and flown to Miami to face charges.

Rivera has avoided trouble before. State prosecutors in Miami pursued up to 52 possible ethics and campaign finance violation charges against Rivera related to his personal use of campaign funds and a $1 million contract he had with a Florida gambling company, but investigators in 2012 decided to bring no charges in part because the statutes of limitation had expired.

Federal investigators were looking into a possible tax evasion case stemming from the same allegations, but so far it has come to naught. And when he first ran for the U.S. House, questions were raised about Rivera's claim on state finance disclosure reports that he worked for the U.S. Agency for International Development when the agency had no record of him doing so.

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