Melissa Ketunuti Slaying: Exterminator Jason Smith Charged

It's the brutal murder of a philadelphia pediatrician. Jason smith, an exterminator, spotted going to her home. And alex marquardt is in philadelphia with the latest. Reporter: Jason smith was... See More

It's the brutal murder of a philadelphia pediatrician. Jason smith, an exterminator, spotted going to her home. And alex marquardt is in philadelphia with the latest. Reporter: Jason smith was arraigned last night and ordered held without bail. This is a man without a criminal background, no connection to the doctor. But reportedly, a long history of anger problems. This surveillance photo is what led investigators to 36-year-old jason smith, as he walked through the neighborhood where mr. Melissa ketunuti loved. Abc news is learning more about smith, the exterminator who police say showed up at the home of ketunuti to handle her rodent problem. They got into some type of argument. It went terribly wrong. At that point, he struck her while she was in the basement, knocked her down, strangled her to death. And ultimately start the fire. Reporter: Smith admitted to the brutal murder. Sources telling abc news affiliate wpvi, that smith told police that ketunuti had del belittled him. At some point, it was solemn. But other points it was sort of like he was in a fog. Reporter: Smith is now charged with murder, arson, abuse of a corpse, and risking a catastrophe. Cory owns a coffee shop on ketunuti's street. They saw ketunuti walking home from doing errands. And just steps behind her, smith. 45 minutes later, we see the same guy walking past. He looked a little more disheveled and has gloves on. Reporter: Police say after the murder, smith circled ketunuti's block twice, before heading off to another job. A family friend of many years, told abc news he was a problem child growing up. He had behavior and anger issues. He also liked to set things on fire. People like mr. Smith basically walk around with a huge chip on their shoulder. And they feel so inadequate and so insecure, that any perceived belittlement of them will set them off. Reporter: And just a short while ago, we received a statement from the ketunuti family reading, melissa was a source of joy to everyone in her life. Her passing has left an enormous gap in our lives. And the family requests privacy to mourn. As for jason smith, we next expect to see him in court in three weeks. George? Alex, thanks. Let's get more from our "gma" legal analyst, dan abrams. You have the confession, dan. You have the tapes. How do they begin to mount a defense? This is story of everyone's nightmare, right? You invite someone in to fix something and something happens. You have an alleged confession. The only defense you can think of is a manslaughter type of defense. There was no intent to commit murder. It was a heat of the moment thing that came up. The problem for him is what happened afterwards. Now, legally, that shouldn't matter. Right? The question legally should be, what was his intent? What were his actions when he did that? But it is impossible to ignore what happened afterwards. And that is, of course, setting the body on fire. How do judge juries balance out? On the other hand, so brutal. On the other hand, no premeditation. A judge and jury, jury in particular, is going to look at all the facts. Going to look at exactly what happened. And I think this is why it's hard for him because when people, in a case like this, where it may not be an issue of did he do it, but why? Those are tough cases for the defendants to win because most of the time jurors look at what happened, they look at the victim and say, this is simply inexcusable. Dan abrams, thanks very much.