By Jeremy McDermott
BBC News, Medellin
With precise intelligence, apparently impeccable timing and serious firepower, rebels from Colombia's National Liberation Army (ELN) were able to spring one of their top leaders from prison last month.
The 7 October rescue freed Carlos Marin Guarin, who also goes by the name of Gustavo Anibal Giraldo, but is better known by his alias of "Pablo" or "Pablito".
It took place as he was about to be moved from the prison in the region of Arauca, near the Venezuelan border, to the capital, Bogota.
Four ELN rebels entered the prison, led by a woman, who threw her boss a pistol. The rebels blasted their way out of the jail, killing one guard, wounding another and sending a further six scurrying for cover.
Waiting outside were two motorcycles and a van with more heavily armed rebels giving covering fire. "Pablo" jumped on the back of a motorcycle and was believed to be in Venezuela less than an hour later.
Pablo was the highest-ranking ELN rebel to have been captured in the five decades the guerrillas have been trying to overthrow the government. So his escape was an embarrassment for the government, leading President Alvaro Uribe to suggest there had been inside help.
"We gain nothing from increased security if there is corruption in that security," said Mr Uribe, a day after the break-out.
Pablo, captured in Bogota in January 2008, never admitted he was a member of the ELN, saying he was a simple farmer from Arauca.
The ELN - responsible for attacks like this 2001 bombing - has been in decline in recent years
But after his escape, the ELN published a communique on its website saying that what it called "Operation Che Guevara" had been the result of two years of planning and was carried out by the rebels' "special commandos".
An investigation has been launched into the escape. All prison personnel in Arauca have been moved to other installations across the country and a reward of $900,000 (£550,000) has been offered for information leading to Pablo's recapture.
In any other country, a 1,500-strong Marxist rebel force would be the top threat to national security.
But in Colombia, the ELN is an almost-forgotten force, the headlines taken by the more powerful Revolutionary Armed Forces of Colombia (Farc) and an array of drugs cartels and right wing-paramilitary groups.
The ELN has been in gradual decline since its peak in 1999 when it numbered 4,000 fighters and was able to kidnap people from airplanes, boats, vehicles and homes, across Colombia.
While the Farc concentrated on building up its war machine and in the 1980s turned to the drugs trade for finance, the ELN focused more on political work.
Its leader until 1998, a former Spanish priest Manuel Perez, forbade his troops to have anything to do with the drugs trade on ideological grounds.
But Pablo appears to have a very different outlook.
"Pablo is a committed Marxist Leninist, but has no problems with making tactical alliances with drug-trafficking groups. The ends justify the means and the ELN needs money," said Gerson Arias, an expert on the guerrilla group at the Bogota-based think-tank Fundacion Ideas para La Paz.
There have been talks in the past between the government and the ELN to find a negotiated settlement to the conflict, the most recent being between 2005 and 2007 in Havana, Cuba.
But there are elements within the ELN high command vehemently opposed to any form of talks, including Pablo.
"The failure of the last round of talks between the government and the ELN was in no small part thanks to Pablito and those within the ELN who think like him," said Mr Arias.
Pablo is, according the military intelligence, in command of three of the ELN's five "War Fronts", all close to the Venezuelan border.
"Pablo is an important figure in the ELN and his area of operations in Arauca is a zone where the rebels have deep roots in the local communities, where they still enjoy a level of support," said Armando Borrero, an academic and security analyst.
In Arauca, a bitter war is under way between the Farc and the ELN for control of the strategic routes into Venezuela, the drugs crops in the area and a multimillion dollar narcotics smuggling operation there.
And with Pablo in the field again, it seems likely that the ELN will regain vigour, particularly given his longstanding ties to Arauca.