Del mouthed "What the ..." and went to the door and stopped.
Del had no illusions about his abilities. He had been a decent and meticulous conservator and his attention to detail was useful in his current job, but his real skill was in reading body language.
And he honestly considered leaving the room again because isabella was movinng with a jerky intensity that suggested she might bite his head off if he so much as breathed let alone commiserated with her on the loss of her adored mother.