Accidental death occurs. People die because of accidents. This type of death can occur accidentally. These parents will never forgive themselves. I'm sure some contemplate suicide. No one suffers in the aftermath of this more than them. Punishment or incarceration would serve no real purpose other than to satisfy certain bystanders' vengeful emotions.
"The knowledge and prudence of the poor themselves, are absolutely the only means by which any general and permanent improvement in their condition can be effected." - Thomas Malthus