French officials say the main suspect in the beheading of a French transportation company manager has admitted to police he carried out the killing that authorities have called a terror attack.

Yassine Salhi, a deliveryman with a history of ties to Islamic extremists, remained in custody Sunday along with his wife and sister.

Security officials say investigators have found no links to any international terror group in the attack Friday. They spoke on condition of anonymity because the investigation is continuing.

Salhi, arrested Friday, was to be transferred to counterterrorism police headquarters outside Paris. He allegedly crashed a truck into a U.S.-owned chemical warehouse and hung his employer's head on the factory's gate. Officials say he sent a "selfie" of himself and the victim to a Canadian mobile phone number.