Cyril Wecht: Forensic Pathologist
Robert Curley, 32, began to grow ill in August 1991, entering the hospital in Wilkes-Barre, Pennsylvania, for a series of tests before he finally died in September. His doctors went through several diagnoses for his burning skin, numbness, weakness, repeated vomiting and rapid hair loss. Just before he died, he became more agitated and aggressive, so he was transferred to a hospital that could test for heavy metal exposure. Sure enough, he had elevated levels of thallium in his system—a substance used in rat poison before being banned in 1984.
A search of his worksite turned up bottles of thallium salts for a chemistry lab, but none of his co-workers had experienced symptoms. The levels measured in Curley at autopsy were so high it was clear that he'd been deliberately poisoned, and his death was ruled a homicide. As Cyril Wecht describes it in Mortal Evidence, his brain had swelled so much it had pushed down into the spinal column.
Suspicion turned to the home, and it was determined that Curley's wife and stepdaughter also had elevated levels of thallium in their systems, but not to toxic levels. Yet investigators found only a tea thermos that showed traces of the poison.
At a dead end, authorities approached Dr. Frederic Rieders of National Medical Services, a private toxicology lab in Willow Grove with extensive testing abilities, to do a more thorough analysis of the tissues. Rieders requested more samples, so Joann Curley agreed to have her husband exhumed. Hair shafts were removed, along with toenails, fingernails, and skin samples.
Dr. Rieders conducted a segmental analysis on the hair shafts to devise a timeline of thallium exposure and ingestion. The hair strands from Curley's head were sufficiently long to plot almost a year of his life prior to his death. Concentrations of thallium were measured over the course of nine months, with spikes and drops that suggested a systematic ingestion long before Curley had begun his job at the university. Clearly, that was not where he had first received his exposure to thallium. There was also a massive spike just a few days before his death that suggested intentional poisoning. At that time, his family had brought in some food and his wife had been alone with him. The culprit seemed clear and Joann Curley was charged.
The prosecution prepared for trial, calling in some big-hitters.
"I was an expert, with Michael Baden and Fred Rieders, for the DA," says Wecht. "I was the only one to testify at the preliminary hearing and I went through the entire forensic pathology and toxicology stuff that the three of us had prepared. It was a beautiful case because it had to do with the sequential chronological testing of a hair from its follicle to its tip. It showed the peaks and valleys of his poisoning. When he was away, he had a valley and when he was home or with his wife, he had a peak."
His role, he points out, was to interpret the toxicological findings in terms of cause of death. "The forensic toxicologist can come up with the technical methodology and findings, but the pathologist is needed to talk about cause of death and relate it to the science and symptoms and critical episodes. It's a joint effort."
In a plea deal, Joann Curley confessed to using rat poison to enrich herself on her husband's life insurance payment. She received a sentence of 10 to 20 years in prison.