A Missouri man was sentenced on Tuesday to 12 years in federal prison after he twice tried to purchase a chemical weapon on the dark web and pay for it with Bitcoin as part of a plot to poison a woman who had ended a relationship with him, prosecutors said.
The man, Jason William Siesser, 46, of Columbia, Mo., pleaded guilty last year to one count of attempting to acquire a chemical weapon and one count of aggravated identity theft, according to federal court records. He appeared remotely during the sentencing hearing in U.S. District Court in Jefferson City, Mo.
Prosecutors said that when he placed the orders for dimethylmercury, Mr. Siesser used the name of a youth who had been placed in his custody through the group home company that he had been working for.
Exposure to a few drops of dimethylmercury, a highly toxic organomercury compound, can be fatal, according to the American Council on Science and Health. A permit is required to purchase the clear, sweet-smelling liquid, which has few uses outside of scientific research and is classified as a chemical weapon when used in a way that it was not intended. Its lethal effects have received widespread attention for their role in the death of a professor at Dartmouth College after a 1996 lab accident.
Mr. Siesser, in August 2018, ordered three 10-milliliter units of the chemical — enough to kill about 300 people — for the equivalent of $150 in cryptocurrency, according to investigators, who said that during a search of his home they had found writings about his being brokenhearted and vowing to do harm.
“They say I should let it go But my hatred’s just too strong,” Mr. Siesser wrote, according to prosecutors. “Letting go of anger is the right thing But it makes me feel so strong I dream about your ending You burn up in flames You suffocate on your own blood Your soul completely drained.”
Christopher Slusher, a lawyer for Mr. Siesser, said in an interview on Tuesday that his client, a former teacher who had served in the military, had been suffering from mental health issues.
“He expressed remorse to the court,” Mr. Slusher said. “He has never been in trouble before this.”
Investigators said that Mr. Siesser had been the custodial guardian of two minors and had used various combinations of the first, middle and last names of one of them on the orders for the toxic substance.
The youth said Mr. Siesser had told him that he wanted to be an assassin and kill those who had wronged him in the past, including Mr. Siesser’s ex-wife and the woman who broke off her relationship with Mr. Siesser after three dates, according to the affidavit.
Mr. Siesser had previously attempted to purchase dimethylmercury from a legitimate internet chemical supplier, but the sale was refused when he did not have the required permit, the authorities said.
That was when, the criminal affidavit said, he turned to what he thought was a seller on the dark web and became ensnared in an undercover operation. He acknowledged to the would-be seller that his acquisition of the chemical posed a risk of death to anyone who came into direct or indirect contact with it and said he planned to use it soon after receiving it, the authorities said.
In August 2018, Mr. Siesser signed for a package that had been delivered to his home. He believed it contained dimethylmercury, but an inert substance was enclosed instead.
Investigators said that Mr. Siesser had read about a scientist who died after being exposed to the dimethylmercury. It was not immediately clear if the scientist was Karen E. Wetterhahn, a professor of chemistry at Dartmouth College and the founding director of Dartmouth’s Toxic Metals Superfund Research Program.
In 1996, as Dr. Wetterhahn transferred the toxin from one container to another, a drop or two of the dense liquid dripped onto her latex glove near her thumb. Less than a year later, she died after developing severe neurological impairment and fading into a coma.
When Mr. Siesser was interviewed by investigators, they said, he told them that he wrote fictional stories about men exacting vengeance on ex-girlfriends.
“In one story, a man used a fertilizer spreader to lace a woman’s yard with asbestos, which ultimately killed her decades later,” the affidavit said. “In another story, a man locked a woman in scuba gear in a submerged box so she would die when her oxygen tank was depleted.”