A Minnesota man has been charged with killing his sober living facility roommate in June with thallium after investigators discovered his multiple internet searches — and purchases — of the highly toxic metal.

Stuart Hanmer, 35, faces a second degree murder charge, with intent but not premeditated, for the June 22 death of 33-year-old Cody Ernst,  InForum reported.

Ernst fell ill on May 15, reporting to his fiancee that he was fainting, vomiting, dizzy, and nauseated. The next day, she found him in the bathroom unresponsive and not breathing and called 911.

He was admitted to the hospital with “seizure-like activity,” a police report said. Days later, he checked himself out of the hospital against doctors orders but didn’t make it far before he was readmitted. He was ultimately transferred to the University of Minnesota Fairview, where screenings revealed thallium poisoning. He died at Fairview on June 22.

Doctors said there was no way Ernst could have been exposed to the level of thallium in his system from environmental sources.

St. Cloud police began investigating upon learning that Ernst and Hanmer were roommates. The spoke with him after Ernst’s death, and Hanmer told them the pair would smoke marijuana and drink coffee in the mornings. He said he’d never heard of thallium poisoning until after his roommate died.

Authorities seized two phones during a search of Hanmer’s home in early August, and that’s ehen they found nearly two dozens searches for thallium in early April The searches asked “how much thallium nitrate is fatal” and “is thallium nitrate the most toxic,” along with a purchase of 5 grams of 99.99 percent thallium metal for $85 on April 5.

The next day, he bought 10 more grams, followed by another 10 grams on May 14. That last shipment was delivered to Hanmer’s post office box, and he signed for it.

The search of the cell phones found more searches about thallium on May 14 and 15, including “how long does it take for thallium to kill you” and “do people seem to get better after initial thallium exposure.”

Hanmer also watched a video showing how to make thallium sulfate.

According to the Brainerd Dispatch, thallium was previously used as a rodent killer and insecticide but was banned in 1965. It has some use in industrial applications, including as a component in infrared optics and high-temperature superconductors.

The paper said that Ernst had lived at the sober house for several months, and Hanmer moved in in early May. It did not say if the two knew each other prior to Hanmer moving in.

Hanmer was arrested last week and booked into Stearns County jail, InForum said.

He was already awaiting sentencing after pleading guilty on August 18 to a felony domestic violence charge in which he threatened to stab an ex-girlfriend with a needle and violated an order of protection against him.

He was previously convicted of assault in 2023 and domestic violence in 2017.

Court documents did not say why Hanmer wanted Ernst dead.