"Lamb to the Slaughter" - I'm the Detective

If I was a detective investigating the murder of Patrick Maloney in “Lamb to the Slaughter” by Roald Dahl, I would have already guessed Mary was the murderer because there was something way too fishy about her plot. One thing I would've done is investigated a little more and ask more questions. Another thing I would do is try to find out if they have been having any problems and study her actions and facial expressions. And I would at least would've known that that huge lamb leg she offered was the murderer weapon because I would think it's just not normal. I would have been a very great detective.