Eight Iraqi officers have been arrested on charges of negligence in investigating an attempt to assassinate Prime Minister Mustafa Al Kadhimi, a senior official said on Monday.
Mr Al Kadhimi escaped unhurt from the November 7 assassination bid, which has gone unclaimed.
Explosive-packed drones were used in the assault. One hit his Baghdad residence while a second one failed to explode and was found on the roof of the house.
A bomb disposal team and forensic experts were ordered to examine the second drone to lift any possible fingerprints, National Security Adviser Qassem Al Araji said.
The teams were then expected to blow up the drone but later revealed they had failed to lift any fingerprints first, Mr Al Araji said.
As a result, a committee investigating the attack decided to arrest the eight officers, including two generals, he said.
An investigation into why they failed to carry out their instructions has been launched, Mr Al Araji said.
The commission "does not want to accuse anyone or any faction". he said. "But what happened indicates there has been negligence."
The attack came two days after two people were killed as security forces clashed with supporters of Iran-backed parties that lost seats in Iraq's October 10 elections.
The violence broke out as demonstrators tried to break into the high-security Green Zone, which houses government buildings and foreign embassies.