For more than sixteen months, Chesterfield police struggled to unravel the mystery surrounding the arsenic-poisoning death of John Mullen, a well-liked physicist and retired research scientist at the McDonnell Aircraft Corporation.
The case now appears to have ended as bizarrely as it began on the sultry morning of June 29, 2004.
It was on that morning that Mullen, after returning to his bluff-top home in Chesterfield following his daily workout, reached into the fridge for a bottle of his favorite mineral-water drink. Little did he know, police confirmed Tuesday, that his long-time girlfriend, Tamara Rallo, had deposited a lethal dose of arsenic that would kill him before nightfall. It took city and county medical examiners five months to finally determine Mullen died from arsenic poisoning. In modern times, a homicide committed with arsenic is extremely rare.
With police breathing down her neck after months of investigative work and an arrest imminent, the 52-year-old Rallo apparently killed herself over the weekend. Her body was found Saturday by family members inside her south St. Louis home. The method of the possible suicide is under investigation, says Chesterfield Police Captain Ed Nestor, adding that no signs of bullet or stab wounds were found on the corpse.
The thin, blond-haired Rallo, owner-operator of Metro Pawn at 8286 St. Charles Rock Road, was to have been charged Tuesday by St. Louis County prosecutors with second-degree murder. Captain Nestor says Rallo was unaware of her impending arrest.
Two weeks after the murder, Rallo left a disquieting voicemail message with Michael Hill, one of Mullen's two sons. Hill recounted the message to the Riverfront Times earlier this year: "'Don't be surprised if you find my body floating in your dad's swimming pool.'"
Mullen met Rallo about ten years ago at a Chesterfield bar and dated her off and on ever since, says Hill, who took the name of his mother's second husband after her divorce from Mullen decades ago.
The relationship, says Captain Nestor, was steadily eroding, with Rallo wanting to get married and Mullen refusing.
Another possible motive, suggests Nestor, was that Mullen provided Rallo the funds to bankroll her pawnshop throughout the years. "But he said he was going to cut her off," Nestor recalls from one of statements Rallo gave police.
"When we interviewed her, she was very talkative. We thought she was very clever and cunning, but she wasn't at all defensive," the police captain adds.
During the initial investigation, Michael Hill says, police told him that Rallo's daughter furnished detectives with a book she found tucked under her mother's mattress, detailing various ways one might kill someone with poison.
Nestor says Rallo placed arsenic in two bottles of Mullen's mineral drink, both of which she put in his refrigerator. A third bottle, which Rallo claimed she had drunk from, was found in her car the day of the murder. Rallo maintained it was the same drink as the other two left for Mullen. But a critical toxicology report completed this summer found no traces of arsenic in that third bottle.
Nestor says the reason for not filing first-degree murder charges was because a jury might question whether Rallo wanted to kill Mullen or just make him extremely ill.