The alleged killing took place during a botched robbery in Bogota last month, officials said.
Surveillance cameras indicate that DEA agent James Watson was the victim of the attack. He died June 21 after the robbers stabbed him, Colombia Reports said.
Colombian authorities have arrested seven men, who are all suspected to be part of a ring of taxi drivers who specialize in robbing their clients.
The U.S. Justice Department is seeking extradition for the suspects, who are wanted on homicide charges.
The gang allegedly drugs or threatens the taxi's customers and takes them to ATMs or their homes to rob them.
Authorities are expecting to make another three arrests, Colombia Reports said.
The suspected accomplices in the killing are: Julio Steven Gracia, Andres Alvaro Oviedo, Edwin Figueroa, Hector Lopez, Omar Fabian Lopez, Angel Mauricio Pulgarin and Wilson Daniel Peralta.