My first impression was more along the lines that the police started to investigate and learned that the mother had gotten "involved" with someone at some point, and the family members and her "boyfriend" (who was mentioned in the tv news story) hadn't known about that beforehand. The police concluded that perhaps she had intentionally run off with this person she had become involved with. Given the potential for embarrassment to those involved, combined with the fact that they're not absolutely sure yet of what went down, they now don't want to say much about it.