Mexico City prosecutors say they have arrested a third suspect in the killings of a photojournalist and four women in a case that drew attention around the world.

City prosecutor Rodolfo Rios Garza said Friday that Cesar Omar Martinez had been arrested earlier in the day on the city's south side.

Martinez is 32, and his name partly corresponds to one mentioned by the second suspect arrested in the case, a former policeman.

Three men were seen by surveillance cameras Friday leaving the apartment building where the killings occurred.

The victims included photojournalist Ruben Espinosa and activist Nadia Vera. Also killed were a 19-year-old aspiring makeup artist, a woman from Colombia and their 40-year-old housekeeper.

Investigators had not yet determined the motive in the killings.