Diego sat inside a car, with a burner phone in his hand with a serious look on his face as if he was battling within himself, to make the needed decision for where Raquel stands now that it's obvious everyone thinks that he's dead.
It was late in the night, but with his car parked outside an uncompleted building site, he couldn't hide how impressed he was towards the detective to make his death more believable. He underestimated him, but Diego underestimated him the most.
Once the seed he has planted in Vladmir's lair grows, not only would the detective benefit from taking the Russo's to prison since he was a witness to their crimes, Vladmir would save his mother if he truly wants the detectives to help him, which unfortunately, it's him that calls the shot from where he lurks in the shadow.