Under the cover of darkness and surrounded by a vast security operation, one of Colombia's most notorious cartel hit men was freed early from prison on Tuesday night, dividing the country over the fate of the killer behind thousands of murders at the height of its searing drug violence.

Jhon Jairo Velázquez Vásquez, alias Popeye, was the top assassin for Pablo Escobar, the infamous drug lord at the head of the Medellin Cartel. Velázquez, 52, claims to have personally killed 300 people and to have had a hand in the murders of up to 3,000 others during the 1980s and 1990s, the height of Escobar's brutal reign. He has also linked himself to the 1989 bombing of an Avianca plane, Colombia's national airline, as Escobar waged war on the state.

Some 200 police officers and five vehicles accompanied Velázquez as he was taken from the Combita high security prison in Boyaca to the capital, Bogota, where he walked free after serving 22 years behind bars.

The complexity of Tuesday's operation — one Colombian newspaper, El Tiempo, even claimed Velázquez had not in fact been transported in the police escort, but in a car with blacked-out windows which slipped out behind them — reflects the sensitivity of his release and the threats that may face him.

Popeye's release is highly controversial given that he had only served three-quarters of his full 30-year sentence for his part in the 1989 murder of presidential candidate Luis Carlos Galán. Critics have also argued that an additional sentence handed down in 2008 meant he should not yet go free.

But Velázquez had testified against former Justice Minister Alberto Santofimio, a rival in the 1990 vote, who was convicted of ordering Galan's killing.

The time discounted for his testimony and good behavior made him eligible for conditional release, which a judge granted last week. Since then, Colombians had waited nervously to hear if he would in fact be freed, as the country's attorney general investigated whether there might be other active cases which could keep him in jail.

'Freedom frightens me, but I'm going to fight for it.'

In the end, the authorities had no choice but to free him, Fernando Hernández Valencia, director of the Colombian think tank Corporacion Nuevo Arco Iris (New Rainbow Corporation), told VICE News.

Hernandez explained that many were disturbed by the release of a man who represented "a chapter of great pain" in Colombia. "Everyone was very much waiting all week to see if he would be released and what it would mean. He was released in Bogota in the middle of the night — and then where would he go?"

There was also anxiety over whether such a prisoner might return to his former activities, or whether his release might unleash violent retaliations, Hernandez said.

Velázquez's confessions make him a likely target for revenge and he has reportedly requested police protection due to fears for his life, which are thought to have been denied.

In an interview with El Tiempo last year, he said he was receiving psychological help to prepare him for the impact of freedom.

"I want to seek opportunities, but some people want me to come out to steal and to kill so that they can kill me, and I'm not going to give them the pleasure," he said. "Freedom frightens me, but I'm going to fight for it."

'I want to teach the young people of Colombia that they don't have to sell their lives for a Mercedes-Benz or for the panties of a beauty queen, like I did.'

Velázquez once freely related his crimes in media interviews, making him a very public figure who loomed large over Colombia, Hernandez said.

But in more recent years he has claimed he wants to be part of the march towards reconciliation in the country, which finds itself at a historic moment with a peace process to end its half-century-long civil conflict with the Revolutionary Armed Forces of Colombia (FARC) well underway.

"I was Pablo Escobar's hit man, cellmate of his worst enemies, friend or enemy of all the dead of the recent wars of Colombia," he said in another interview with the magazine Semana in 2013. "I want to teach the young people of Colombia that they don't have to sell their lives for a Mercedes-Benz or for the panties of a beauty queen, like I did. I hope they give me that opportunity."

Whether he will get the chance he wants is questionable. Colombian media reported that while no details had been released as to his destination after Bogota, it was expected to be Medellin or elsewhere in Antioquia Department, which still remains one of the country's most unstable regions.

El Tiempo cited sources in the attorney general's office as saying that his release implied he had accepted a life in anonymity, alone and far from his loved ones.

He might wish to go into hiding in another country for his security, Hernandez said. However the conditions of his release mean he is unable to do so for a 52-month probation period, and must regularly report to the authorities.

Some relatives of Escobar's victims said that Velázquez had now paid for his crimes. But Federico Arellano, president of the Colombia con Memoria foundation, who lost his father in the Avianca bombing, condemned his release on Twitter. "Victims of the Medellin Cartel reject the order of freedom for Popeye," he said. "24 years and nine months ago today Escobar, Popeye and his cartel ended the lives of 107 passengers in full flight. 25 years of impunity are coming."