SAN FRANCISCO - The motel handyman accused of killing a Yosemite naturalist and three sightseers is scheduled to undergo a radioactive brain scan that death penalty defendants nationwide are using more often, partly in the hope of being spared execution.
A Positron Emission Tomography, better known as a PET scan, will be performed on Cary Stayner some time this month by scientists at the University of California, Irvine, law enforcement sources and a medical official acknowledged this week on the condition of anonymity.
The scan, which can detect brain abnormalities, is one component of a battery of psychiatric tests Stayner is scheduled to take during an evaluation at UC-Irvine that could take more than a day, two of the officials said. It was unclear what other studies would be done.
Federal Defender Robert Rainwater, lead attorney for Stayner, did not immediately return a call Friday. Dr. Joseph Wu, the clinical director of the PET center at UC-Irvine, declined comment.
Stayner is being held at the Fresno County Jail pending his federal trial there in the July 21 felony murder of Joie Armstrong, who worked as a naturalist at the park. He has pleaded innocent in that case and has waived his right to appear during the first hearing on pretrial motions, scheduled for June 8.
Stayner also faces state charges in the murders of Carole and Juli Sund of Eureka and Silvina Pelosso of Argentina, the three sightseers who were killed five months earlier along the western outskirts of the park.
Federal prosecutors, who have presiding jurisdiction because Armstrong was killed in a national park and Stayner was first taken into custody in her death, won approval from U.S. Attorney General Janet Reno to try their case first and to seek a death sentence.
Stayner's attorneys are arguing against the death penalty and have not indicated whether they plan to pursue any kind of mental health defense. Should they decide on an insanity plea, the government has asked it be given enough time to prepare before the mid-October trial.
PET scans are used predominantly in death penalty cases, in the hope that evidence of a possible brain dysfunction might raise reasonable doubt about guilt or be weighed as a mitigating factor against execution. Officials at Federal Death Penalty Resource Council said no one seems to be tracking the impact of the trend.
The technology has been around since the 1970s but was prohibitively expensive until recently. A scan, which takes 30 minutes, costs about $1,500 at UC-Irvine but can run upwards of $3,000 elsewhere.
The growing popularity of the scans has become a topic of debate within legal and medical circles, with arguments centering on the reliability of the science and whether it should be used in trying to explain - or even excuse - criminal behavior.
Outside the courtroom, the scans are currently approved by the government for a limited amount of medical purposes, including treating a variety of cancers, determining whether cardiac patients can benefit from bypass surgery or angioplasty, and locating seizure points in epilepsy patients, said Dr. Robert Carretta, the president of the Society of Nuclear Medicine in Virginia.
''Using PET Scans for studying criminal behavior is not something done routinely nor approved. This would be done under research protocol at an academic institution,'' Carretta said Thursday. from St. Louis, Mo., where his society's annual meeting was being held.
Dr. Helen S. Mayberg, a neurologist at the Rotman Research Institute in Ontario, Canada, has written papers on the subject and testified at trials against the appropriateness of PET Scans in drawing conclusions about criminal behavior.
Mayberg said Thursday that there is no scientific evidence linking brain patterns with homicidal and sadistic tendencies, abnormal sex drive, violent impulse, nor psychopathic and sociopathic traits. And she finds it very troubling that lawyers are using the results to suggest such unproven correlations.
''You don't point to a brain scan and a blue spot and say that's the reason for the serial killings,'' Mayberg said, unaware Stayner was scheduled for such a test. ''That's junk science ...There has to be scientific support for the claim you're making ...You're asking people to weigh evidence that even scientists aren't comfortable with.''
Defense attorneys, however, justify the strategy, noting how case law makes clear their obligation to investigate and present any type of evidence that might explain a defendant's actions. And they say the science, although evolving, is well-regarded and reliable.
''I remember quite a few people saying the same kinds of things about DNA a few years ago,'' said Jeff Thoma, a public defender in Mendocino County.
