The assassination of two Japanese diplomats in Iraq on Nov. 29 was carefully planned, according to the governor of Salahaddin province, where the slayings occurred.
Gov. Hussein al-Juboort said Monday that one group was in charge of collecting information and another carried out the killings.
Hussein said Iraqi police have detained suspects they believe were involved in the shooting deaths of two South Korean technicians Nov. 30 on the same highway as the Japanese diplomats. Hussein supervises the provincial police force.
Hussein believes the murder of the Japanese diplomats -- Katsuhiko Oku, 45, and Masamori Inoue, 30 -- was carefully planned. His opinion matches that of Iraqi Foreign Minister Hoshyar Zebari, who has called it a carefully planned crime by professionals.
U.S. military forces in Iraq have said Oku and Inoue were ambushed by assassins with automatic rifles who were driving three or four vehicles.
Hussein has not released any details on the suspects arrested for allegedly killing the South Korean engineers.
Zebari has said the killings matched the modus operandi of the Muharabat, the intelligence organization of deposed President Saddam Hussein's government. His comments imply that anti-American forces are targeting Japanese.
The Japanese government believes the slaying of the Japanese diplomats and their Iraqi driver was most likely a terrorist attack.
Other foreigners taking part in the U.S.-led reconstruction efforts in Iraq have been targeted on the same highway, which runs north from Baghdad to Tikrit and Mosul.