The FARC's 34th Front is among the group's most entrenched and fiercest fighting units, based in the dense, water-logged jungles around Quibdo. Its members repeatedly violated unilateral cease-fires declared by the FARC leadership in Havana during elections and Christmas holidays.
A spokesman for the FARC in Havana declined to comment, saying the rebels' negotiators were still investigating the incident and would comment at a press conference Tuesday.
Santos, who was re-elected in June, has staked his presidency on reaching a deal with the FARC. But he's struggled to overcome doubts from conservative opponents and members of the military who fear he's ceding too much power to the rebels.
“While the FARC talks about peace in Havana, here they're committing all sorts of atrocities,” said former Peace Commissioner Camilo Gomez, adding that the talks could unravel without a major overhaul to demand the FARC demonstrate its commitment to peace. “This could be the straw that breaks the camel's back.”
Analysts say that the capture appears to have been accidental. Securing the general's release could be difficult: after a decade of heavy losses inflicted by the U.S.-backed military, the FARC leadership's operational command over its estimated 8,000 troops has been greatly reduced and just getting messages to the front lines could take several days.
Alzate, 55, is among Colombia's most-decorated soldiers. A graduate of the U.S. Army War College and Command and General Staff College in Kansas, he previously oversaw the military's anti-kidnapping unit. In January, Santos named him commander of the newly established Titan Task Force, a 2,500-man counterinsurgency force operating from Quibdo.