The parent, particularly the mother, always feels responsible (guilty) when a child dies. They feel deep down that it is their fault something they did or something they didn't do could have made the difference.
When my 10 day old adopted son started having problems and we rushed him to the hospital, I was afraid whatever it was was my fault and he would be taken away from us. There was no way I could have passed a lie detector test right then. It turned out that it was a congenital heart defect but until we were told I was convinced somehow I had caused him to be near death.
This same son was killed in a traffic accident when he was 18, again I felt responsible for reasons that I now know are ridiculous. This mother many have done something to this child, she is suspect #1 but she also could be suffering extreme guilt over not keeping the baby safe from a stranger.
Thank you for that post. I’m so sorry for your loss.