Colombian security forces on Monday killed a senior rebel in the Marxist terrorist group ELN (Ejército de Liberación Nacional), the second largest guerrilla army in the region.

The BBC reports that during a confrontation between the rebels and the security forces which took place in the Santander province, 42-year-old ELN fighter Jose Daniel Perez was killed.

The Colombian military claims that Daniel Perez, who goes by the moniker “One-eyed Lucho,” was behind an ambush in October that resulted in the deaths of 11 soldiers and one police officer.

While continuing to make strides towards peace with the largest terrorist group in the region, FARC (Fuerzas Armadas Revolucionarias de Colombia), Colombia has had far less success at approaching peace with the ELN.

Although the smaller terrorist group and Colombia had been meeting for exploratory talks, October’s ambush seriously derailed any immediate chances at a bilateral ceasefire.

After the ambush, President Juan Manuel Santos immediately ordered that security forces step up their attacks on the ELN, despite the rebels’ insistence that the ambush did not undermine their desire for peace.

On Monday, Santos took to social media to congratulate the security forces on their kill and the affect it had on the terrorist group. On Twitter, he wrote, "Our military and police inflict a heavy blow against the ELN. They neutralised alias One-eyed Lucho and weakened the [rebels'] eastern front."

Colombia, which has been in a war with Marxist groups for over 50 years, appears to be at point when it is ready to make some serious changes concerning its treatment of rebels.

The Guardian reports that Colombia has decided, for the first time ever, against extraditing a captured FARC rebel to the United States to face drug trafficking charges. An executive resolution by President Santos says that Juan Vicente Carvajal, a FARC rebel, will not be turned over to a court in New York to face charges.

The gesture is no doubt a sign of diplomacy, as the March deadline for negotiations between FARC and Colombia approaches.