She took a picture of him in front of his science project...at school.
I'll also not that she has been his step mom since he was an infant.
As kids disappearing from school is VERY rare, the likelihood of ANY scenario we can think of is also VERY small.
Basic categories of what could have happened are: He's at the school (likely VERY bad!), he walked away on his own (not so bad), a relative took him away (maybe or maybe not bad - Sometimes there are hidden secrets in families) or a stranger took him from the school (VERY BAD, and also VERY DIFFICULT to do without being seen.)