An alleged mass murderer was mistakenly released from custody in Iraq, and the U.S. military now is offering a $25,000 reward for information leading to his capture.

Mohammed Jawad An-Neifus, suspected of involvement in the murder of thousands of Iraqi Shiites (search), was released from the Bucca Internment facility at Umm Qasr (search) on May 18, the U.S. military acknowledged in a statement.

The Shiite victims' remains were found at a mass gravesite in the southern city of Mahawil.

According to the statement, An-Neifus was detained by U.S. Marines near the city of Hillah (search) on April 26 and was turned over to Army Military Police on April 29.

An officer from the Judge Advocate General's Corps conducted a routine screening of An-Neifus on May 18, and nothing he said alerted the officer to his true identity. He was then cleared for release, the military said.

In the statement, the military said it accepted sole responsible for An-Neifus' erroneous release and is conducting a thorough investigation to ensure no recurrences.