I would venture to say she was still in shock about what happened.I've seen the mother on several different news interviews and found her demeanor to be disturbingly calm and emotionless.
When I got the news that my son had died I didn't cry or showed any emotion at all
until a couple of days after his funeral. I was in such a state of shock that all I could
think about was his funeral and talking care of his estate. After this was completed, the
reality of loosing my son hit me hard, really hard. I broke down and cried my eyes out.
Which I still do several times a week.