A fifth tourist was injured in the attack but survived
A man accused of being involved in the murder of four French tourists has escaped from police in Mauritania before he was due to go on trial.
Sidi Ould Sidna is accused of shooting the tourists as they ate a picnic in southern Mauritania last December.
Mr Sidna, thought to be in his 20s, asked to use the toilet after questioning in a courthouse in the capital Nouakchott.
He ran out of the door and police lost him in the crowd.
Deputy prosecutor Moustapha Ould Said said Mr Sidna escaped, and that "the fugitive was able to divert the attention of the policeman that was guarding him", the Associated Press (AP) quoted him as saying.
A witness quoted by AP said they saw Mr Sidna ask to use the toilet and the policeman guarding him leave the bathroom to talk to a group of friends.
Mr Sidna is said to have been wearing civilian clothes and so was quickly able to blend into the crowd once he fled the building. Police were reportedly still searching for him hours after his disappearance.
Mr Sidna and a co-accused, Mohamed Ould Chabarnoux, are suspected of killing the French tourists, near the southern town of Aleg, on behalf of al-Qaeda.
Mr Sidna was detained in neighbouring Guinea-Bissau after a manhunt across West Africa.
Those shot were enjoying a family holiday in Mauritania. A fifth person survived the attack.
Mauritania is a former French colony and its south enjoys relative stability.
The north of the country is generally regarded as less safe for travellers.
The killings prompted the organisers of the Paris-to-Dakar rally to cancel this year's event and hold it instead in South America.