Ariel Castro listens in the courtroom during the sentencing phase of his trial Thursday, August 1, in Cleveland alongside defense attorneys Craig Weintraub, left, and Jaye Schlachet. He pleaded guilty last week to 937 counts, including murder and kidnapping, in a deal that dropped a possible death penalty in exchange for life in prison plus 1,000 years. Here's a look at the moments leading up to his sentencing. 
Michelle Knight speaks during the sentencing phase for Ariel Castro Thursday, August 1, in Cleveland. "I will live on," Knight said in her statement to Castro. "You will die a little every day." 
Castro enters the courtroom Friday, July 26. He was arrested in May and accused of holding three young women captive for nearly a decade. 
Amanda Berry vanished a few blocks from her Cleveland home on April 21, 2003. She was 16. She spoke in a video released on YouTube on Monday, July 8, thanking people for support and privacy. Berry, Gina DeJesus and Michelle Knight escaped from a Cleveland home on May 6 after being held captive for nearly a decade. 
Georgina "Gina" DeJesus was last seen in Cleveland on April 2, 2004, on her way home from school. She was 14 when she went missing. 
Knight was last seen on August 22, 2002, when she was 21. 
FBI agents and other law enforcement officers stand outside Castro's home in Cleveland on May 9. 
Castro hangs his head while talking with his public defender, Kathleen DeMetz, during his arraignment on May 9. 
Ariel Castro was charged on May 8 with kidnapping the three women. 
Investigators remove evidence from the house on Seymour Avenue in Cleveland where the three women were held. 
An FBI forensics team meets outside the house where three women were held as they investigate the property. 
Cleveland Deputy Chief of Police Ed Tomba, center, speaks at a news conference to address details of the developments. 
The house where the three women were held captive in Cleveland was the home of Ariel Castro, who was arrested and is being held pending charges in the case. 
FBI agents remove evidence from the house May 7. 
A police officer stands in front of the broken front door of the house on May 7, where the kidnapped women escaped. 
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- Anna Salter: Ariel Castro believed he had "consensual sex" with chained women
- Salter: Most predators justify their behavior; it's not sexual, it's psychopathic
- If Castro believed he had an addiction, she says, why didn't he seek help?
- Salter: Forgiveness must be earned: Castro has not taken a step to atone
Editor's note: Anna Salter is an internationally known expert on sex offenders, a psychologist and the author of three books on sex abusers, including "Predators." She has worked at assessing and treating sex offenders and victims for more than 35 years and lectures and consults throughout the United States and abroad. She also writes mystery novels.
(CNN) -- "There are so many ways of being despicable it quite makes one's head spin. But the way to be really despicable is to be contemptuous of other people's pain." -- James Baldwin
No doubt most people who listened to Ariel Castro's self-serving monologue during his sentencing hearing on "consensual sex," and "harmony in that house," wondered at his sanity and his definition of "monster." Sanity, however, is judged by reality testing and not by caring or compassion. Human cruelty is not a disease or a mental illness, although it is a plague on humankind.
As someone who has worked with violent offenders for 35 years, I can tell you unequivocally the number of offenders who deny, minimize or justify their behavior far outweigh the number who take responsibility. Never mind the tortuous loops the mind has to jump through. If the sex was consensual, what exactly were the chains and locks for? There is no limit to the mind's ability to rationalize.
A man who beat a 3-year-old to death told me that he only committed violence when "the situation called for it. I never did anything I didn't have to do." When asked how he feels about the boy's suffering, he replied, "I guess I don't feel anything." When asked if he saw himself as a criminal, he said, "I know that's what I'm seen as but no, I don't."
A man whose brother took him in when he had no place to go after being released from prison raped his benefactor's 12-year-old daughter -- his niece -- and stabbed his brother 12 times when he came to her rescue.
When asked why he did this, he replied: "I was drinking. It just happened. ... You can't blame anybody for the rain. You can't blame anybody for nothing."
We are familiar with whole cultures justifying violence as extreme as genocide. Why are we surprised when individuals do the same? Violence is almost always denied or rationalized -- after the fact, if not before.
Victim's kin: Castro home a 'dungeon' 
Toobin: Castro's remarks 'repulsive' 
Victim: I won't let Castro define me Even violence that appears impulsive is usually related to thinking patterns and beliefs that justify it. Such rationales are important to protect self-image. Again it was Baldwin who said, "No man is a villain in his own eyes."
As to Castro's claim that he had an illness, a sexual addiction, there is a difference between urges and behaviors. Castro could have dealt with his urges by seeking help. Medication and treatment have been available for sex offenders for well over a decade.
Would they have worked? Who knows? He didn't try. He made a decision to live out his sexual fantasies, not to try to control them. In treatment, at the least he would have learned how not to reinforce the fantasies through violent pornography. At least by telling someone, he would have had some check on his behavior.
Castro may not have chosen the fantasies that dominated his dreams, but he chose to act on them -- for more than a decade. Even the most persistent urges are not present 24 hours a day. All Castro needed was for 51% of him to have an attack of conscience for a few minutes and want to release those women long enough to open a door. In more than a decade he never had it.
In fact, he tormented his victims not only in sexual ways but in nonsexual ways as well: He showed them TV coverage of their families grieving. He told one that her family didn't care about her. He fed them once a day. He beat a pregnant woman until she miscarried. None of these speak to sexual urges; these acts speaks to psychopathic traits: the lack of a conscience, lack of caring about other human beings, callousness, lack of guilt and lack of remorse -- in short, malevolence, the desire to harm another human being gratuitously while being contemptuous of her pain.
Even now, he has shown no genuine remorse or regret. What we saw at the hearing instead was a cocoon of aggressive narcissism wrapped so tightly Castro could proclaim with a straight face that chained women were having sex with him consensually. Yet at the same time he asked for their forgiveness.
No doubt there are those who will advise the victims they must forgive in order to move on. I disagree. Forgiveness is not a gift; it must be earned. Atonement and change must precede forgiveness or else it is an empty gesture.
It is difficult to imagine how much Castro would have to change for forgiveness even to be legitimately on the table. I'm not sure his sentence is long enough for that to happen, and to date, he has not taken a single step.
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The opinions expressed in this commentary are solely those of Anna Salter.
