Three people with suspected ties to al-Qaida have gone on trial in Mauritania for the 2009 murder of a U.S. citizen.

A court in Mauritania's capital, Nouakchott, opened the trial Tuesday for Mohamed Abdallahi Ould Ahmednah, Didi Ould Bezeid and Mohamed Mahmoud Ould Khouna.

The three are accused of shooting and killing American teacher Christopher Leggett in Nouakchott in June 2009.

Al-Qaida's North African branch claimed responsibility, saying it killed Leggett because he tried to convert Muslims to Christianity.

The teacher worked for an aid group that provided computer classes for local residents.

Al-Qaida's North African branch, al-Qaida in the Islamic Maghreb, is believed to be behind a string of attacks and kidnappings in Mali, Niger and Mauritania in recent years. The group operates across Africa's Sahel region.

Some information for this report was provided by AP, AFP and Reuters.