She held out the watch that her husband took such pride in. He instantly recognized it. The same thought crossed both of their minds at the same time. Clear signs of a struggle and large amount of blood on the floor next to her husband's watch could very well mean that she was covered in Antonin's blood. There were spells that could be cast to find out for certain, but there wasn't time and she didn't know the incantations off the top of her head. Somehow though, she just knew.