Marcel did a complete sweep of the Base after the attempt on Arianna's life. He tightened security and had the body taken out and the scene cleaned up while Samson returned safely to his Den.
As for Arianna, he took her to bed after giving her coconut milk to calm her nerves. She had received quite a shock today. Thankfully, she fell asleep, giving Marcel time to sort out the mess.
"Give me the report," Marcel said, seated down and wouldn't stop tapping his feet anxiously against the floor.
He refused to leave Arianna's side, which means they were gathered in his living room while she slept soundly in his room. He left her hours ago and she nearly died. Marcel was not repeating the same mistake, at least until he knows what he was dealing with here.
Luca told him, "The woman was one of the staff."