Complex sentence: The van had been rented by a Moroccan suspect Driss Oukabir, who was a convicted criminal, had rented the van acording to the Spanish Police was not clear if Oukabir was driving the vehicle or in any way involved in the attack.
Split into simpler sentences: The van had been rented by a Moroccan suspect Driss Oukabir, who was a convicted criminal, had rented the van according to the Spanish Police. It was not clear if Oukabir was driving the vehicle or in any way involved in the attack.