A U.S. Army soldier pleaded guilty Wednesday to being an accessory to the rape and murder of an Iraqi girl and the slaying of her family, one of the worst atrocities which U.S. forces have been accused of during the Iraq war.

Pfc. Bryan Howard, 20, also pleaded guilty to conspiracy to obstruct justice by lying to his superior officers about the attack last year in Mahmoudiya, 20 miles south of Baghdad.

A sentencing hearing was expected to begin later Wednesday. The maximum sentence for the charges to which Howard pleaded guilty is 15 years.

Howard told the judge he was left behind at a checkpoint while four other soldiers went to rape the girl. Howard said he overheard the four planning the attack.