Jonathan Kellerman_Petra Connor 02 Read Online Free PDF Page B

face.
    Isaac’s neatly typed sheet lay flat on her desk. He sat in the metal chair by the side of her desk. Drummed his fingers. Stopped. Pretended to be nonchalant.
    She read the heading again. Boldface.
    June 28 Homicides: An Embedded Pattern?
    Like the title of a term paper. And why not? Isaac was just twenty-two. What did he know about anything other than school?
    Below the title, a list of six homicides, all on June 28, on or near midnight.
    Six in six years; her initial reaction was
big deal.
For the past decade, L.A.’s annual homicide rate had fluctuated between 180 and 600, with the last few years settling in at around 250. That averaged out to a killing every day and a half. Meaning, some days there was nastiness, others nothing at all. When you considered summer heat, June 28 would most likely be one of the high-ticket dates.
    She said all that to Isaac. He shot out his answer so quickly she knew he’d been expecting the objection.
    â€œIt’s not just the quantity, Detective Connor. It’s the quality.”
    Those big, liquid eyes.
Detective Connor.
How many times had she told him to call her Petra? The kid was sweet, but there was a certain stubbornness to him.
    â€œThe quality of the killings?”
    â€œNot in the sense of a value judgment. By quality I mean the inherent properties of the crimes, the . . .” He trailed off, plinked a corner of the list.
    â€œGo on,” said Petra. “Just keep it simple—no more chi square, pi square, analysis of whatever. I was an art major.”
    He colored. “Sorry, I tend to get—”
    â€œHey,” she said, “just kidding. I asked you to tell me about your statistical tests and you did.” At breakneck speed, with the fervor of a true believer.
    â€œThe tests,” he said, “aren’t any big deal, they just examine phenomena mathematically. As in the likelihood of something happening by chance. One way to do that particular analysis is to draw comparisons between groups by examining the distribution of . . . the pattern of the scores. I did exactly that. Compared June 28 with every other day of the year. You’re right about homicides clustering, but no other date presents this pattern. Even summer effects tend to manifest on weekends or holidays. These six cases fall on various days of the week. In fact, only one—the first murder—took place on a weekend.”
    Petra reached for her mug. Her tea had gone cold but she drank it anyway.
    â€œWould you like some water?” said Isaac.
    â€œI’m fine. What else?”
    â€œOkay . . . another way to look at it, is to simply examine inherent base probabilities—” He’d punctuated his words with index-finger jabs. Now he stopped, blushed even more intensely. “There I go again.” Another long, deep inhalation. “Let’s take it issue by issue. Start with weapon of choice, because that’s a discreet— It’s a fairly simple variable. Firearms are the clear favorite of L.A. murderers. I’ve looked at twenty years’ worth of one eighty-sevens and seventy-three percent have been carried out with handguns, rifles, or shotguns. Knives and other sharp objects are next, at around fifteen percent. That means those two modalities account for nearly ninety percent of all local murders. The FBI’s national figures are similar. Sixty-seven percent firearms, fourteen percent knives. Personal weapons—fists, feet—account for six percent and the rest is a mixed bag. So the fact that neither a gun nor a knife was used on any of the June 28 cases is notable. As is the nature of the fatal injury. In every data bank I’ve checked, blunt force homicides never rise above the level of five percent. They’re a rare occurrence, Detective Connor. I’m sure you know that better than I.”
    â€œIsaac, I just closed two cases. A bare-fist blow to the head and a broken neck via martial