This is definitely a sad, messy situation with no simple, convenient solutions or path to closure.
I would underscore that it is extremely odd that she was able to obtain a visa with that criminal history. If it were the case that a country's law enforcement/judicial system took such a long time to "process through" felonious acts that such history would legitimately not appear on the country's police certificate, then wouldn't the US consulate in such a country not be aware of the legal slowness?
And in countries where fraud is so high that its citizens could pay off someone for a "police certificate" that hides criminal history, we see an abundance of examples on VJ of visa applicants waiting for months or even years until the consulate can make a decision on issuing the visa.