Perhotin's curiosity is overwhelming. He cannot but be suspicious of Dmitri, so he decides to investigate the truth of Dmitri's explanations. He goes to Grushenka's maid and learns about the brass pestle, then goes to Madame Hohlakov's to confirm Dmitri's story about the money. Madame Hohlakov is annoyed at being awakened so late at night, but on hearing the reason, she excitedly declares that she has never given anything to Dmitri.
Perhotin has no choice; it is his duty to report all that has happened to the police. But when he arrives, he finds that others also have news to report to the police. Marfa has sent word to them that Fyodor has been murdered.
An investigation follows, and it is decided that Dmitri Karamazov must be apprehended immediately. Dmitri is arrested and pleads that he is innocent of the crime, but no one believes him — not even Grushenka, who bursts into the room crying that she drove him to commit murder but that she will love him forever. On cross-examination, Dmitri confesses that he is guilty of hating his father but maintains that in spite of this, he did not murder the old man. His guilt, however, now seems more definite to the authorities. Eventually, Dmitri makes more admissions and confesses that he did know of the 3,000 rubles that his father had. And he admits that he was indeed in desperate need of that exact sum to repay his debt to Katerina Ivanovna. He does not try to conceal facts that seem to implicate him in the murder, and the knot tightens. Questioned more carefully about his activities on the night of the murder, Dmitri accounts for all his moves, including the visit to his father's house. He even admits taking the pestle with him but cannot give an explanation as to why he did. He is completely honest on all but one matter — the origin of the large sum of money he had when arrested.
Dmitri is ordered to undress and submit to a thorough search. The officers go through his clothes, searching for more money, and find additional bloodstains; they decide to retain his clothing as evidence. Dmitri is then forced to realize the seriousness of his situation and tells where the money came from. He explains about the orgy with Grushenka and reveals that he actually spent only half of the 3,000 rubles Katerina gave him; the other half he has saved. But, having decided to commit suicide, he saw no value in the money any longer and decided to use it for one last fling.
Other witnesses are called in, and all agree that Dmitri has stated several times that he spent 3,000 rubles on the orgy and needed 3,000 to replace the sum.
When Grushenka is brought in for her testimony, Dmitri swears to her that he is not the murderer. She, in turn, tries to convince the officials that he is telling the truth, but she is sure that they do not believe her.
The officials complete their examination of witnesses and then inform Dmitri that they have arrived at a decision: he must be retained in prison. He is allowed to say good-bye to Grushenka, however. Deeply apologetic for the trouble he has caused her, Dmitri asks her forgiveness. Grushenka answers by promising to remain by him forever.
In this book, all of Dmitri's past lies and braggadocios coalesce and smother his pleas of innocence. Logically, one could say that Dmitri had the motive for the murder and was, as confessed, even at the scene of the crime. The conclusion seems obvious. Dostoevsky has carefully arranged the details and circumstances in such a manner that the case against Dmitri is wholly convincing; the man is guilty. But there is another dimension to the investigation. As the officers review Dmitri's life, Dmitri also reviews his life and begins to realize the nature of his past and its meaning. It is this realization that greatly aids his reformation. Only in the light of such dire circumstances is it possible for someone like Dmitri to evaluate all his acts and take full responsibility for them.
Grushenka has never spoken with Father Zossima, but the wisdom of the elder is a part of her newly discovered self. She tries, for example, to take the blame — to take Dmitri's sins upon herself — by crying out that she is responsible for the crime. She played with the passions of an old man and his son, and, as a result, murder was committed. Later, when Dmitri swears to her that he is innocent, she is convinced of the truth of what he has said. She needs no other proof; this alone illustrates the extent of her love for Dmitri. This is the deeply transforming love that Zossima taught.
At first, Dmitri thinks it only a matter of time before he will be able to convince the officials of his innocence, but as the questions and the evidence begin to mount around him, he begins to see the seriousness of his position. It is then that he undergoes a change. He realizes the need for a transformation. He confesses almost every detail of his life and is bitterly ashamed. Because the officials write down the sorry details of his past, he is even more deeply ashamed.
He is quick to see that he is not guilty of the murder but that he is indeed guilty. So often he boasted of killing his father and so often he wished for his father's death; now all that is on trial and he stands literally naked before the probing magistrates. The shame of his entire life is revealed in all its disgusting corruptness.
In many of his novels, Dostoevsky is concerned with the actions of police — how officials conduct investigations. Dostoevsky especially details what questions are asked. Throughout the interrogation of Dmitri Karamazov, Dostoevsky does not distort the processes of justice. The officials are depicted as honest and penetrating men, finally arriving at a reasonable conclusion. Dmitri is not tried by brutally caricatured sadists. The logic of the evidence exists.
There is a bit of irony in Dmitri's consideration of Smerdyakov. He is positive that the murder could not have been committed by the cook. He is, according to Dmitri, "a man of the most abject character and a coward."
Perhaps Dmitri's most redeeming act is this: he judges himself and finally welcomes the suffering to be imposed upon him. He assumes his share of the guilt for the murder of his father and he assumes the responsibility for all the deeds of his past. To the officials, he exclaims, "I tell you again, with a bleeding heart, I have learnt a great deal this night. I have learnt that it's not only impossible to live a scoundrel, but impossible to die a scoundrel."
Dmitri's dream is further proof of his redemption. When he dreams that he is crossing the steppes on a cold winter day, passing through a burned village, a gaunt peasant woman holds a crying baby in her arms, and Dmitri's heart overflows with anguish and sympathy for such poor people. He is overcome with compassion and love for these and for all humanity. Thus when he wakes he is ready to accept his suffering and exclaims, "By suffering I shall be purified." He is ready to undergo a period of trial and emerge a new and responsible character.