I watched the LVMPD press conference live, this afternoon. They picked up one of the men, at the airport, Friday afternoon. From info that he gave them, they were able to get a search warrant, for the house where O.J. was staying. The cops recovered weapons and clothing, used in the incident. Those, combined with his own statements, gave them enough evidence, to place him under arrest and for the DA to lay these charges.
O.J.'s current defense is that he was conducting a sting operation, to recover his own stolen property. There's just ONE problem with that: it is ILLEGAL, for a private citizen to conduct such a sting, especially using weapons. According to the complainants, O.J. was barking orders to his henchmen and there was some waving about of guns. Hence, the conspiracy and assault charges.