The serial killer whom police call the "Baseline Killer" shoots his victims in the head, sometimes using medium- or large-caliber weapons, according to examinations of victims in five of six shootings attributed to him.

Another suspected serial killer known as the "Serial Shooter" used small-caliber weapons or a small-gauge shotgun in three of five shootings, autopsy reports said. The victims linked to him were hit in the torso, chest or neck.

The reports released Wednesday by the Maricopa County Medical Examiner's Office provide a glimpse into the massive police investigation of killings that have gripped the Phoenix area and put community watch groups on high alert.

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The serial killers are suspected of randomly attacking at least 41 people. The Serial Shooter is thought to have first killed in May 2005, while the Baseline Killer is believed to have begun killing in September.

According to the autopsies, the victim of at least one shooting linked to the Baseline Killer was attacked from close range. Autopsy reports from two shootings said a medium- or large-caliber bullet was used.

An autopsy report related to the sixth shooting victim had not yet been released by authorities.

One shooting attributed to the Baseline Killer might have involved more than one gunman, according to the medical examiner's office. An autopsy report said a business owner saw "suspects" standing over Tina Marie Washington with a drawn handgun.

Police spokesman Sgt. Andy Hill said the Baseline Killer sometimes strikes up a conversation just before he attacks.

That means that in many of the killings and sexual assaults attributed to him, the victims had an opportunity to get away.

"People do get intuitive feelings, and they do need to follow those feelings," Hill said.

Katherine Ramsland, a professor at DeSales University in Pennsylvania who teaches about serial killers, said there could be two reasons the Baseline Killer talks to victims before striking.

"He's probably checking out how vulnerable they seem, whether they're seeming to be on guard, armed with a weapon or alone," Ramsland said. "And he's picking out certain types of people who are satisfying something for him, fitting a particular criteria that fulfills his inner fantasies."

The Serial Shooter probably is less selective and simply trying to hit somebody, said Ronald R. Scott, a Phoenix firearms and ballistics expert.

"We're all trained to shoot to the middle of the body," Scott said. "That's how we don't miss."