Mexico City's top prosecutor says a suspect has acknowledged he was in the apartment where four women and a photojournalist were killed last week.

Prosecutor Rodolfo Rios told the Televisa network Thursday that the suspect was one of three men whom surveillance cameras recorded leaving the apartment building.

Rios declined to identify the man, who he said was previously convicted of rape and causing injuries and served nearly 10 years in prison.

Rios also wouldn't say whether the suspect had confessed to either the killings or the robbery police say was apparently carried out at the apartment.

The victims included photojournalist Ruben Espinosa, who fled the Gulf Coast state of Veracruz because of intimidation.

Rios said investigators had not yet determined the motive in the killings.