What evidence suggests Montresor committed the perfect crime in "The Cask of Amontillado"?

Montresor is unbelievably thoughtful and careful when executing this murder in revenge for the wrongs Fortunato has done him. He knows just how to manipulate people to avoid suspicion, and his thoughtful planning at each stage of the murder is evidence that he commits the perfect crime. First, he claims that he never "gave utterance to a threat"; he tells no one about his plans to kill Fortunato. Further, he says,

It must be understood that neither by word nor deed had I given Fortunato cause to doubt my good will.

He allows Fortunato to continue to think that they are on good terms so that Fortunato does not guard himself against Montresor's machinations.

Next, Montresor has chosen a night in which he can be in costume: a night during the carnival season. After he finds Fortunato in the streets, drunk, Montresor dons a "mask of black silk" and draws a long, black cloak around him so that no one will be able to identify him. Anyone who sees the two men together will not know that it is Montresor underneath the black costume, and so he will not be connected with Fortunato's disappearance.

Third, Montresor emptied his house of servants without appearing to realize that he has done so. Rather than give everyone the night off, which could raise suspicions later, he gives them "explicit orders" that they should "not [...] stir from the house" though he, himself, will not be home all night. Of this, he says,

These orders were sufficient, I well knew, to insure their immediate disappearance, one and all, as soon as my back was turned.

Finally, because of the manner in which Montresor disposes of Fortunato, there is literally no evidence of the crime. There is no blood, no body to hide or get rid of, and no murder weapon to be found. By walling Fortunato up in such an extensive underground vault, Montresor all but insures that no one will ever find Fortunato's body.

What evidence suggests Montresor committed the perfect crime in "The Cask of Amontillado"?

In my opinion, the clearest evidence that Montresor has committed the perfect crime is that he has not been prosecuted for the crime of killing Fortunato.  The story is narrated by Montresor, but not the Montresor of the time of the story.  Instead, the Montresor who narrates the story is looking back at the time that he killed Fortunato.  It is decades later when he is telling the story.  If he has not been caught and punished after all these years, he must have committed the perfect crime.

In the last lines of the story, Montresor reveals that he has gotten away with the crime for something like 50 years:

Against the new masonry I re-erected the old rampart of bones. For the half of a century no mortal has disturbed them. IN PACE REQUIESCAT!

What evidence suggests Montresor committed the perfect crime in "The Cask of Amontillado"?

There are three indications in Edgar Allan Poe’s short story “The Cask of Amontillado” that serve to illustrate Montresor’s success in murdering Fortunato with impunity.  The first indication is not found in the text per se, but rather can be inferred from the fact that the story is related in retrospective fashion; in other words, it is clear from the first-person narration and use of the past tense throughout that the murder occurred at some point in the past.

The next indicator that Montresor succeeded in getting away with murder occurs at the outset, when the narration sets the stage for the story to follow and for the planning that went into the crime’s preparation.  Montresor, in his narration, informs the reader of the prerequisite for the perfect crime:  having the deed go undetected:

What, according to Montresor in "The Cask of Amontillado," makes a perfect crime?

It isn't Montresor's recipe for a perfect crime that he addresses, but it is what Montresor feels is the perfect revenge. He wants revenge against Fortunato for "the thousand injuries" Montresor feels Fortunato has done to him. In the first paragraph, Montresor states what must occur in order for revenge to be successful.

"A wrong is unredressed when retribution overtakes its redresser. It is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong."

First, revenge isn't successful if the person seeking revenge allows it to control him. Montresor must not allow his desire for revenge to consume him. Sometimes people want revenge so much that they destroy themselves in the process. Montresor says this must not happen. This is why he says he must "punish with impunity." He will make Fortunato pay for his insults, but Montresor will be free from any harm to himself.

The second part of successful revenge is that Fortunato must know that Montresor is the person who is seeking revenge against him. The person seeking revenge must let the other person know who he is. Montresor would never allow someone else to act in his place; he must committ his crime of vengeance himself.

What, according to Montresor in "The Cask of Amontillado," makes a perfect crime?

Montresor feels like a crime is not the perfect crime unless you get away with it. 

This story is about a man who meticulously plans and carries out another man’s murder. He gives no reason for the murder except for some unmentioned, vague “injuries” of which we get no specifics. Nonetheless, Montresor feels he has cause to murder Fortunato.  

I must not only punish but punish with impunity. A wrong is unredressed when retribution overtakes its redresser. It is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong. 

Basically, what Montresor is saying here is that if he does not get away with the murder, he will have failed to achieve perfect revenge. Therefore, he plans to get Fortunato at Carnival time, when he will be drinking and feeling lighthearted. This will allow Montresor to catch him off guard. To lure Fortunato in, Montresor tells him he has a special cask of wine for him to evaluate.

Montresor’s plan is to take Fortunato into the catacombs and brick him into the wall. By the time Fortunato realizes what is happening, it is too late. At the end of the story, we learn it has been fifty years since Montresor bricked Fortunato up into the wall, and he has apparently been able to get away with it.

I hastened to make an end of my labour. I forced the last stone into its position; I plastered it up. Against the new masonry I re-erected the old rampart of bones. For the half of a century no mortal has disturbed them.

It seems Montresor did get away with it. So who is he telling the story to? Does he have a guilty conscience? What is the significance of the line “In pace requiescat” (rest in peace)? Is it intended ironically, or does Montresor feel bad? We can only speculate answers to these questions.

According to Montresor, what makes a perfect crime?

In the opening paragraph of Edgar Allan Poe's short story "The Cask of Amontillado," the first-person narrator Montresor vows revenge against the perceived insults he has endured at the hands of Fortunato. Montresor has planned to murder his so-called friend. For Montresor, the crime of killing Fortunato can only be considered a perfect crime if two things are part of the plan. First, the crime must be undetected; second, the victim must understand exactly who is perpetrating the crime against him. Montresor's crime should go unnoticed and, moreover, he needs Fortunato to recognize Montresor is the one killing him. He indicates this by saying,

I must not only punish, but punish with impunity. A wrong is unredressed when retribution overtakes its redresser. It is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong. 

In the first sentence of this statement, Montresor uses the word "impunity," which is defined as being without fear of punishment. In the third sentence, he makes it clear that, as the "avenger," he needs to make certain the victim understands exactly what is happening. In the end, Montresor's plan works to perfection, and he claims in the final line that the bones of Fortunato were never discovered.

Did Montresor commit a perfect murder in "The Cask of Amontillado"?

At the beginning of Poe's classic short story "The Cask of Amontillado," Montresor elaborates on his definition of the perfect revenge. After vaguely describing the ways Fortunato had caused him harm, Montresor provides his definition for the perfect way to get revenge by saying,

I must not only punish, but punish with impunity. A wrong is unredressed when retribution overtakes its redresser. It is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong. (Poe, 1)

Montresor is essentially saying that he must not only punish his enemy but do so without getting caught. His revenge would not be complete if he were to suffer the consequences of his actions or not make himself known to his enemy. Given Montresor's strict definition of revenge, one could argue that he successfully committed the perfect crime.

Montresor carefully plans and executes the perfect crime by cleverly acting amicably in front of Fortunato and gaining his trust. Montresor is careful to approach Fortunato during the chaotic carnival season, which gives him the opportunity to conceal his identity behind a mask. Montresor then manipulates Fortunato's pride and uses his love of fine wines to persuade his enemy into entering his catacombs.

Once Fortunato is in Montresor's vaults, he continues to give his enemy alcohol to further impair Fortunato's judgment before suddenly shackling him to the back wall. Montresor then builds a wall around Fortunato, burying him alive. At the end of the story, Montresor mentions that for a "half of a century" nobody has disturbed Fortunato's bones, which reveals that he got away with murder.

Since Montresor made himself known to his enemy and never suffered the consequences of murdering Fortunato, one could argue that he committed the perfect crime.

According to Montresor in "The Cask of Amontillado," what makes a perfect crime? What makes Montresor's crime a perfect one?

    If every home today had as vast a system of catacombs as Montressor's in Edgar Allan Poe's classic short story, "The Cask of Amontillado," then the perfect crime would become routine. Montressor has indeed committed the perfect crime.

For the half of a century no mortal has disturbed them. In pace requiescat!

Although Fortunato's "crime" is never disclosed, Montressor states frankly that it must be met with "impunity"--exempt from punishment. He has certainly succeeded. Montressor has managed to lure Fortunato to his own resting place among the bones of centuries dead Montressors: a fitting and symbolic final stop. Montressor has enacted the ultimate punishment without actually carrying out the murder with his own hands; he will simply allow time to dictate Fortunato's final hours. There are no witnesses, and the body will never be found. Every aspect of his plan, from the false bottle of Amontillado to the hidden trowel and cement, has worked to perfection. He is able to experience the satisfaction of Fortunato's demise and has done so in a matter that exposes his victim to the mental realization of the horrible, helpless situation. And unlike the narrator of "The Tell-Tale Heart," whose madness and guilty conscience eventually overwhelms him, Montressor can apparently live happily with his conscience. It is that rare crime of perfection.