How does this short story represent dramatic, situational, and verbal irony?

"Lamb to the Slaughter" definitely has all three of those types of irony. The verbal irony might be the least prevalent, so I'll start there.  One of the last things the investigating officers say is about the murder weapon.  

"Personally, I think the weapon is somewhere near the house."

"It's probably right under our noses. What do you think, Jack?"

The line is ironic, because the murder weapon really is right under their noses....

"Lamb to the Slaughter" definitely has all three of those types of irony. The verbal irony might be the least prevalent, so I'll start there.  One of the last things the investigating officers say is about the murder weapon.  

"Personally, I think the weapon is somewhere near the house."

"It's probably right under our noses. What do you think, Jack?"

The line is ironic, because the murder weapon really is right under their noses.  They are eating the weapon as they speak.  

Another example of verbal irony is when Mary says the following line:

I know that Patrick would never forgive me if I let you stay in the house without offering you anything to eat.

It's ironic, because Patrick can't forgive her either way any more.  He's dead.  

The dramatic irony of the story is also the part where the officers are eating the lamb.  Dramatic irony occurs when the audience knows something that all or most of the characters do not know.  In this case, the reader knows that the lamb is the murder weapon.  The police do not; therefore, they go about happily eating it.  

Situational irony is when something happens that is the opposite of what the reader would normally expect to happen.  I can think of two clear examples of situational irony in the story.  The first is that Mary Maloney clubs her husband to death with a chunk of meat.  The story opens with her being the perfect doting wife.  She's practically a member of the Stepford Wives Club.  It is completely unexpected that she would kill her husband.  The second major piece of situational irony is how Mary deals with the murder.  She is cool, calm, and collected.  She goes about setting an alibi and getting rid of the murder weapon.  That one really took me by surprise.