From an interview with paramilitary commander Ever Veloza (alias "Hernan Hernandez") in El Espectador:

When I was commander in Uraba and he [General Rito Alejo del Río] was commander of the 17th Brigade, I kidnapped two people from inside the Brigade, who had been detained by the army. I took them out of their cell...

How did you kidnap someone from inside an army brigade?

With the complicity of the army. I took them out in a car belonging to the army. We took the prisoners out of the cell, they were from the FARC’s 5th Front…. I went into the Brigade, took them to Buenaventura and disappeared them.

…I moved around as if I owned the place. I went into the army brigade, the police barracks, and did what I wanted…. In Uraba when we started, we left the bodies where we had killed them. After a while, the armed forces started to pressure us: they would let us keep working, but we had to disappear the bodies. And that’s when we started digging mass graves. It started as a request of the armed forces. They said to us, “disappear them and we’ll let you keep working.”