Prosecutors say the American woman killed in Florence, suffered two fractures to her skull before she was strangled. They added that they detained the prime suspect following analysis of DNA found on a condom, a cigarette and under Ashley Olsen's fingernails.

Florence prosecutors identified the suspect as Tidiane Cheik Diaw, a 25-year-old Senegalese man who arrived in Italy a few months ago illegally.

Prosecutors said witnesses reported seeing Olsen and Diaw leaving a disco early Friday morning and enter her apartment in Florence's historic center. Investigators said he had taken her cell phone, put his own SIM card in it and used it.