I have heard rumors that "Lamb to the Slaughter" is a true story. Is it?It's not really important but it's just curiosity...

Well, we don't really know and Dahl gives no indication,
however, if we think for one minute about the way the story is structured and the
precision with which Dahl is known to have crafted his writings, we can see there are
serious doubts. First of all, it is highly unbelievable that a woman such as Mary
Maloney who is described as such a loving and caring wife, attentive to her husband's
every need, should suddenly at a drop of a hat (or at the drop of a leg of lamb), show
herself to be a criminal mastermind able to outwit the pooled intellect of the police. I
wonder whether Dahl had heard a rumour of a story of the perfect crime and worked on
that to produce the unforgettable story that we have now.