For years, Bruce Bagley was the go-to academic expert on drug trafficking in Latin America, sharing his knowledge with Congress, journalists, prominent attorneys and even the Central Intelligence Agency.

But in a stunning turn of events, a Manhattan federal judge on Tuesday sentenced the retired University of Miami professor to six months in prison for his role in secretly laundering millions of dollars on behalf of some of the same bad guys he dedicated his life to studying.

"I am ashamed of my irresponsible behavior," Bagley, struggling to hold back tears, told Judge Jed Rakoff while appearing remotely via Zoom. "I have spent my life as an academic working to understand and improve conditions in many countries in Latin America, and to be here today is the greatest departure from the life that I have aspired to."

Rakoff said a sentence of up to five years, as recommended by federal guidelines, would be "irrational" and "overly punitive" for Bagley, who is 75 and in ill health.

But he said some prison time, however modest, was required to deter others in positions of authority from engaging in similar behavior.

"If there is anyone in the world who knew that this kind of activity was criminal it was Dr. Bagley," said Rakoff, who recommended Bagley be allowed to complete his sentence at a prison with a good medical facility.

Bagley's transition from writing textbooks to carrying out what prosecutors called a "textbook case of money laundering" came from his dealings with another criminal defendant: Colombian businessman Alex Saab, who is accused of paying kickbacks to members of Venezuelan President Nicolás Maduro's family and inner circle to win overvalued state contracts.

Bagley was introduced to Saab by a longtime government informant, Jorge Luis Hernández, better known by his nickname Boli. Years earlier, Bagley helped Boli avoid deportation to his native Colombia, where Bagley said he faced a certain death from right-wing paramilitary groups who then dominated drug trafficking along the the Caribbean coast.

At Boli's urging, Saab asked for Bagley's help securing a U.S. visa for his son and later agreed to hire him as a $1,000-per-hour consultant for an investment in Guatemala. Then starting in late 2017, Bagley began receiving monthly deposits of approximately $200,000 from a purported food company based in the United Arab Emirates. Additional funds were wired from Switzerland, bringing to nearly $3 million the amount he collected from Saab, according to prosecutors.

Bagley then transferred 90% of the money into the accounts controlled by the informant, believing they would be forwarded to Saab's U.S. attorneys, who were then secretly meeting with federal investigators to explore a possible resolution of his own case.

Bagley kept a 10% commission for himself and continued to accept the cash even after one of his accounts was closed for suspicious activity.

"Yes. It is corruption," the professor told Boli in one recorded conversation from a December 2018 meeting, adding that he knew Saab was importing food on behalf of the Maduro government. "They have imported the worst quality products with inflated prices, and they have filled their pockets with money."

It's not clear what motivated Boli to betray Bagley. He did not respond to a text message seeking comment.

Before his downfall, Bagley had studied organized crime in Latin America for decades. He chaired the University of Miami's Department of International Studies, published numerous books and articles, and was quoted regularly by the media.

"If you are too ostentatious and too public, you attract a great deal of attention," Bagley told The Associated Press in a 2012 interview on drug trafficking in Mexico.

Bagley also served as a consultant to a number of U.S. federal agencies — the FBI, DEA, CIA and the Pentagon — as well as the governments of Argentina, Colombia, Ecuador, Mexico and Panama, according to a 24-page resume in court filings.

In seeking leniency, attorneys for Bagley presented him as a cross between an idealistic poverty fighter and an absent-minded professor who would forget to pay a utility bill or run out of gas while driving because he was too absorbed in his research.

But evidence introduced at the last minute by prosecutors presented a darker side.

At the same time Bagley was fielding calls from policy makers in Washington, he and Boli — the informant — were hobnobbing with shady politicians from across Latin America, including presidential aspirants from Paraguay and the Dominican Republic, as well as a Colombian governor, Kiko Gomez, then under criminal investigation for homicide.

In 2015, Bagley signed an affidavit in which he affirmed that Gomez had no ties with right-wing paramilitary groups. But in a sentencing memo seeking leniency, lawyers for Bagley said he had refused to sign such an affidavit despite being offered $25,000 because his academic research had led him to conclude that the politician was indeed tied to the militias, which are designated a terrorist organization by the U.S.

"Either Bagley's representation about his research in his sentencing submission is false, or he signed a false affidavit in 2015," prosecutors argued in a filing late last week. "In either event, the Government respectfully submits that Bagley's misrepresentations are relevant to the Court's determination of the appropriate sentence to impose."

Bagley's attorneys said the document was based on only initial findings and that Bagley refused to provide a more in-depth report of the kind sought by Gomez.

Joshua Goodman reports for the Associated Press.

Copyright 2021 AP. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.