When Drew Peterson was brought into court on charges that he murdered his third wife Kathleen Savio, he was in a good mood. He yelled jokes to reporters about how "spiffy" his red prison jumpsuit was and called his shackles "bling."

Peterson is, of course, also a suspect in the 2007 disappearance of Stacy Peterson, his fourth wife. He insists he is an innocent man.

Think of how you'd respond to being dragged into court on murder charges, especially if you were wrongly accused. You might be terrified or confused or enraged at the injustice of your plight, but you wouldn't be all smiles, spewing one-liners.

So how can Drew Peterson do it?

To have any hope of understanding Drew Peterson, one first has to understand human empathy. Empathy is the ability to resonate with the feelings of others to such an extent that one actually experiences some of their joy or grief or anxiety. It is a remarkable and inexplicable quality that we too often take for granted. The fact that a friend can be brought to tears by a loss of yours, that you can intuit and share the worries or hopes or pride of your partner in life, or that the hunger of children thousands of miles away could spur you to action on their behalf is a tribute to this miraculous force.

Empathy does even more, though. It helps us contain our anger and our destructive impulses, because we can imagine how it might feel to be the object of that rage. It also helps us gauge what is appropriate language and behavior in various situations, again because we can imagine how others are likely to respond to us. We can put ourselves in the shoes of our friends or neighbors or loved ones.

I believe empathy is an essential ingredient in experiencing guilt, as well. If you can't imagine the injuries you may have done another person-can't feel their pain in any measure-then you aren't likely to worry over any harm you've done them. The absence of empathy is the growing place for antisocial and narcissistic traits that set a person adrift from the interpersonal ties and sense of personal responsibility that bind the rest of us.

Drew Peterson may be largely devoid of empathy. That's why he just doesn't get the fact that lobbing jokes to reporters while being dragged into court on charges he murdered a young woman is bizarre and macabre. It's why he believed he'd come across as credible on television during the media tour he orchestrated after the disappearance of Stacy Peterson. It's why he probably is confident a jury will acquit him (which, of course, it could). Peterson may not be able to put himself in the place of others-at all.

One of the most toxic manifestations of having no empathy, of course, is that it leaves those without it free to inflict suffering on others. There's no wincing at causing them pain, even death. In the forest of pure narcissistic and antisocial traits that grow in soil without roots of empathy, only self-preservation and one's own needs matter. No one and nothing else really does.

If Drew Peterson killed Kathleen Savio or is responsible for the disappearance of Stacy Peterson or both, he isn't worried about any of that. He's busy with the opportunity to showcase what he believes is his extraordinary charm and intelligence and wit. And he thinks you and I and every reporter and every judge and every juror will be mesmerized.

Dr. Keith Ablow is a psychiatry correspondent for FOX News Channel and a New York Times bestselling author. His newest book, "Living the Truth: Transform Your Life through the Power of Insight and Honesty" has launched a new self-help movement. Check out Dr. Ablow's Web site at livingthetruth.com.

Dr. Keith Ablow is a psychiatrist and member of the Fox News Medical A-Team.