Defense Probing Brain to Explain Yosemite Killings

Cary Stayner is California’s most notorious murder defendant, accused of last year’s Yosemite slayings. He confessed to slitting the throat of one victim, burning the bodies of two others and beheading a fourth.

But was Stayner destined from birth to commit those gruesome crimes? Was he predisposed--by biology or perhaps some childhood injury--to murder?

Stayner’s defense team hopes to find answers to such provocative questions with a radioactive brain scan performed at UC Irvine that can detect if the motel handyman suffers some sort of cerebral abnormality.

The procedure, known as positron emission tomography, or a PET scan, is increasingly popular among defense attorneys seeking to block executions. Scores of the tests have been conducted on criminals, both at UC Irvine and at other PET scan centers around the country.

In some instances, the results--displayed in graphic multicolored images that show brain activity--are credited with convincing jurors to spare convicted murderers.

“Now we can look inside the mind of a murderer,” said Adrian Raine, a USC neuroscientist and pioneer in the evolving field. “If a defense attorney can show to a jury there is a physical and functional deficit, it’s very compelling.”

But some experts ridicule the use of such high-tech tests in the courtroom as junk science--unreliable evidence that proves no link between genetics and murder.

“It’s alarming to me these are being used in a court of law--the science that would back this up just isn’t there,” said Evan Balaban, a neurobiologist at Neurosciences Institute in La Jolla. “There’s no body of reputable research to suggest there’s a unique PET signature for people who commit murder.”

In the case of Stayner, who faces possible execution if convicted, legal experts doubt that evidence of some brain dysfunction would soften a jury horrified by the brutality of the crimes.

“It’s a huge leap from abnormal brain activity to beheading and burning bodies,” said Mike Rustigan, a San Francisco State University criminology professor. “Defense attorneys are looking to say there’s a medical basis for this evil. I’d say they’re flailing.”

Stayner’s defense team goes to federal court in Fresno today to ask for a venue change and to argue against the push by prosecutors for the death penalty. Stayner is slated for an October trial in the killing of Joie Armstrong, a Yosemite naturalist beheaded outside her cabin last July. Because the crime occurred in a national park, the case is being heard in federal court.

He also stands accused on state charges of killing Eureka residents Carole Sund and her 15-year-old daughter, Juli, and a family friend, Silvina Pelosso of Argentina. The disappearance and deaths of the three Yosemite sightseers just outside the park in February 1999 drew national attention.

Stayner’s attorneys are arguing against the death penalty, but have yet to hint whether they will steer toward an insanity defense and have not said how they would use the PET scans. One law enforcement expert suggested that the defense wants proof of some biological abnormality in hopes of getting prosecutors to strike a deal that would spare Stayner’s life.

Federal marshals drove Stayner from Fresno County Jail to UC Irvine last week for the PET scan and a battery of other psychological tests, a law enforcement official said.

Officials at UC Irvine refused to discuss Stayner. The university’s PET scan center has conducted 4,000 of the tests over the last 15 years, but only about a dozen in criminal cases.

“We’re treating this patient the way we’d treat any other patient,” said Joseph Wu, clinical director of UC Irvine Brain Imaging Center. “We’re doing a routine test of brain injury. The implications or inferences drawn from this must be left up to the jury.”

PET scans have been around since the 1970s, and are used mainly for treating some types of cancer, epilepsy, stroke and other maladies of the brain. The procedure got pulled into the courtroom in the mid-1980s when former UC Irvine researcher Monte S. Buchsbaum began using PET scans as part of his testimony in criminal cases.

Defense attorneys saw it as a way to provide physical evidence to bolster expert testimony about the psychology of criminals facing the death penalty.

In some cases they got results.

PET scans conducted by Buchsbaum, now with Mount Sinai Hospital in New York, were credited with keeping convicted murderer Barry Wayne McNamara off death row after he killed his parents, sister and niece in Santa Barbara County.

In a celebrated 1992 case, a retired New York advertising executive strangled his wife and threw her body out their 12th-floor apartment window to feign a suicide. After a PET scan was introduced showing brain defects, the district attorney agreed to a reduced plea of manslaughter.

But in other instances, the weight of horrific crimes overwhelmed any physical evidence of brain dysfunction. A PET scan found brain abnormalities in convicted serial killer Randy Kraft. But an Orange County jury was unswayed, and Kraft was sentenced to death in 1989.

PET scans determine the parts of the brain that are consuming glucose and thus showing the most activity. A picture generated by computer marks the various regions of activity in bright colors, usually red for the most active and blue for the least.

Raine helped produce a landmark study in the early 1990s on 41 murderers in California. Using PET scans, he found a lack of activity in the prefrontal cortex, the part of the brain that acts like a sort of emergency brake to regulate and control behavior under duress. Genetic factors, birth complications or head trauma in childhood can damage this key area of the brain, Raine said, presaging a possible future of criminal behavior.

He noted that psychological issues of background and upbringing have been accepted courtroom fodder for a generation. The jury simply weighs such evidence and decides the merits, Raine said. “How is physical evidence any different?”

Jurors can be dazzled by the display. Christopher Plourd, a San Diego criminal defense attorney, remembers well the first time he used PET scans in the early 1990s during a murder trial.

“Here was this nice color image we could enlarge, that the medical expert could point to,” Plourd said. “It documented that this guy had a rotten spot in his brain. The jury glommed onto that.”

But prosecutors have increasingly challenged admissibility of PET scan data. Many fear that the multicolor images, along with the patina of medical credibility the tests enjoy in the eyes of some, give defense attorneys a powerful propaganda tool.

“We should as much as possible steer away from junk science until this has more of a track record, more of history and less of a potential to mislead jurors,” said Robert A. Pugsley, law professor at Southwestern University School of Law.

Foes say that the technology proves nothing, that studies haven’t established a conclusive connection between biology and homicidal rage. Scientists, they argue, are still wrestling to understand what links exist between the brain and complex behavior.

Judges have been given broad discretion to admit the test results, particularly during the penalty phase of a capital case. In a landmark 1993 ruling, the U.S. Supreme Court said judges should serve as gatekeepers to ensure that scientific evidence is “not only relevant, but reliable.” But interpretations of that ruling have varied widely.

Brain experts, meanwhile, remain cautious about mixing PET scans, MRIs and other clinical tests with court proceedings. The Society of Nuclear Medicine, an international medical body made up of radiological experts, approved guidelines in 1996 urging scientists to avoid drawing conclusions from brain scans that cannot be supported by large-scale studies.

Even advocates like Raine, who believes a link exists between criminal behavior and biology, advise caution.

“We must be very careful with this,” Raine said. “We must not jump to conclusions. We shouldn’t let people out of the electric chair because they’ve got an abnormal brain scan. But we should consider it.”