A Mexican official says the federal attorney general's office has launched an investigation into arrests by local officials of eight suspects in the killing of three news photographers in the eastern state of Veracruz.

The official says federal authorities are skeptical of state officials' claims to have solved the case based on confessions. The official spoke Friday on condition of anonymity.

Suspect Juan Carlos Hernandez Pulido was allegedly detained last week with one victim's ID, and local authorities say he led them to the others.

The New York-based Committee to Protect Journalists also has voiced skepticism because of the lack of evidence in the case.

Veracruz State Attorney General Amadeo Flores Espinosa alleges that all the suspects are members of the New Generation gang allied with the powerful Sinaloa Cartel.