Man Charged with Poisoning Roommate with Thallium
A Minnesota man has been charged with murder after police say he fatally poisoned his roommate using thallium, a banned and highly toxic heavy metal once used in pesticides.
The suspect, Stuart Hanmer, 35, was arrested Wednesday in connection with the death of Cody Ernst, 33, who died on June 22 after weeks of mysterious and debilitating illness. The two men had been living together at a sober living facility in St. Cloud, Minnesota.
According to a criminal complaint obtained by St. Cloud Live, Ernst began experiencing unusual symptoms shortly after Hanmer moved in during May. He suffered repeated hospitalizations for severe pain, vomiting, and neurological decline. By the time of his death, Ernst had been paralyzed and placed on life support. His former fiancée, Cat Williams, described his suffering as “the most horrific, awful way anybody could pass.”
Doctors at the University of Minnesota Medical Center eventually discovered “an extremely high and lethal level of thallium” in Ernst’s body on June 20, just two days before his death.
Online Searches Raise Suspicion
Investigators soon focused on Hanmer, uncovering a disturbing trail of online activity. According to the complaint, Hanmer allegedly conducted multiple Google searches about thallium, including:
- “How long does it take if thallium poisons you”
- “How much thallium nitrate is fatal”
- “Is thallium the most toxic”
- “Is thallium metal in elemental form toxic”
Authorities also allege Hanmer searched how to buy the substance and made three online purchases in April, totaling $162.56 for 25 grams of thallium metal. Records show he signed for a package at the sober living facility on May 14 — two days before Ernst’s first hospitalization.
In addition, investigators discovered Hanmer had watched YouTube videos in April and May on how to make thallium sulfate, a dangerous compound.
Arrest and Charges
When questioned by police on July 7, Hanmer reportedly downplayed any knowledge of thallium and said he and Ernst had simply spent time drinking coffee and smoking marijuana together. However, investigators concluded there was enough evidence to charge him.
Hanmer was arrested with assistance from the FBI and booked into Stearns County Jail. He now faces a charge of second-degree intentional murder. His bail has been set at $4 million without conditions or $2 million with conditions. His next court date is scheduled for September 19.
Thallium: A Deadly Poison
Thallium was once used as a rodenticide and insecticide but was banned in the United States decades ago due to its extreme toxicity. Even in small doses, exposure can cause nerve damage, organ failure, and death. Today, its use is restricted to industrial and electronics manufacturing.
Authorities continue to investigate how Hanmer allegedly obtained the substance and whether any additional safety breaches occurred.
The case has drawn national attention due to the rare use of thallium as a murder weapon, as well as the chilling evidence of deliberate research and purchase of the poison.
