The contractor, reported by local paper El Tiempo to be Andrés Riaño Ravelo, a 41-year-old engineer working for Ismocol SA, was abducted in the municipality of Saravena in the Arauca department, where Ecopetrol maintains a large oilfield and significant operations.

The Bogotá-based oil giant confirmed that an Ismocol employee, a subcontractor of Ecopetrol logistics and transportation subsidiary Cenit, was kidnapped from its office in Saravena.

The office of the attorney general has launched an investigation into ELN ties and has confirmed that it is analyzing security camera footage of the incident. On Twitter, the agency specifically named Nelson Prieto, known as alias “Mompis,” with links to the guerrilla group and a warrant for homicide, according to the attorney general’s office, as an investigation target.

The abduction reportedly occurred around 7:30 am on the same day that UN Secretary-General Antonio Guerres arrived in the country for a two-day trip to discuss the nation’s peace process with Colombian President Juan Manuel Santos and assess the post-conflict progress so far.

ELN, of the National Liberation Army, which are now the country’s last large leftist armed guerrilla group, began formal peace negotiations in Ecuador with the Colombian government last February, just months after a peace deal with the larger Revolutionary Armed Forces of Colombia (FARC) was finalized.

While the group continued to allegedly carry out pipeline attacks throughout the first half of 2017, a bilateral ceasefire was reached by negotiators in September in the lead up to the first-ever visit to the country by Pope Francis. But that ceasefire expired this week, and ELN has seemingly wasted no time reinitiating belligerent actions.

The United Nations had been the lead monitoring organization for years of talks with FARC and agreed to stay on to oversee discussions with ELN. UN head Guerres spent several hours with Santos in Bogotá on Saturday before flying to the department of Meta to visit a FARC reintegration camp on Sunday.

Following three attacks against different sections of the Caño Limón-Coveñas oil pipeline on January 10, President Santos condemned ELN for the incidents and recalled his lead negotiator, Gustavo Bell, from the Ecuadorian capital Quito back to Bogotá.

Santos stopped short of saying that the negotiations would be halted, stressing that “my commitment to peace will be unwavering” and that Bell was being recalled so the principal officials could “evaluate the future of the peace process.”

Colombians will go to the ballot in May to elect a new president. Santos, who will exit after serving a maximum two terms, won the Nobel Peace Prize in 2016 and has been the most strident supporter of peace negotiations with both guerrilla groups while many conservative politicians continue to rail against an accord they believe afforded too many benefits to get FARC to lay down arms.