Manuel “Sureshot” Marulanda, the founder and top commander of Colombia’s main left-wing insurgency (FARC), died of a heart attack after more than four decades fighting a fierce guerrilla war, his rebel group declared.

Marulanda organized the Revolutionary Armed Forces of Colombia, or FARC, as a communist army in 1964.

”Our maximum leader, Manuel Marulanda Velez, died of a heart attack on March 26... in the arms of his companion,” FARC said, Reuters reports.

It seems that Alfonso Cano, already a member of its seven-man leadership, will replace Marulanda as its chief, the FARC said. 59-year –old Cano is known as more of a political leader and negotiator than a military strategist.

Marulanda, whose real name was Pedro Antonio Marin, was one of Colombia's most hunted men. He was last seen in public more than five years ago. Under his command, the FARC grew into a 17,000-member force controlling large parts of the country.

At least 40,000 people have been killed in the last decade alone. Human rights groups condemned the FARC for its role in drug and arms trafficking, kidnapping and killing civilians, and recruiting child soldiers.

”With his death, a chapter of the FARC has closed,” Defense Minister Juan Manuel Santos said on Sunday. “He was someone who has been stuck in the past and always opposed peace,” he added, quoted by the same source.

”He [Marulanda] was an authority figure ... what he did was solve the disputes among the younger commanders,” Pablo Casas, an analyst at the Security and Democracy think tank in Bogota, said.