Elder José Arteaga Hernández, the alleged organizer of the attack on Senator Miguel Uribe Turbay, is now in custody.
The arrest comes almost a month after Uribe was shot in Bogotá while giving a political speech.
Uribe, a prominent critic of the president and a presidential candidate, has been undergoing treatment in intensive care.
Arteaga faces serious charges, including attempted murder, and his arrest is a major step in the investigation.
