A staff scientist at a United States university research institute has been charged with recklessly endangering safety after he allegedly laced a colleague’s water bottle and shoes with toxic laboratory chemicals because the colleague received a promotion he had sought for himself.
Makoto Kuroda, 41, was arrested on April 10, 2026, following an investigation by the University of Wisconsin-Madison Police Department (UWPD) at the Influenza Research Institute (IRI) on the Madison campus. He faces two charges: second-degree recklessly endangering safety and tampering with household products. If convicted on both counts, he could face up to 16 years in prison.
According to a criminal complaint, the victim noticed a strange chemical odour and taste from his water bottle on April 4, having left it open on his desk. He also detected an unusual smell from his shoes and reported both to a colleague, who contacted UWPD. Officers and the Madison Fire Department Hazardous Incident Team responded to the lab on April 7 and collected items that later tested positive for chemicals.
Kuroda did not wait for investigators to name him. He texted a coworker confessing to the act, writing: “I did it. I have also informed the person himself.” He subsequently admitted to police that he had drawn the chemicals from his own work refrigerator, mixed paraformaldehyde and Trizol into a syringe, and introduced the mixture into his colleague’s belongings. He told investigators that 10 millilitres of paraformaldehyde could be lethal if consumed.
Kuroda told police his primary motive was the victim’s second promotion to a position he had wanted. He also cited accumulated frustrations over the colleague’s habit of not wearing a lab coat and safety goggles in the laboratory.
The State Lab of Hygiene confirmed the water bottle tested positive for chloroform, a byproduct of the Trizol mixture used in research at the institute.
A Dane County court commissioner set a $5,000 cash bond at Kuroda’s initial appearance and ordered him to stay away from the University of Wisconsin-Madison (UW-Madison) campus and all its laboratories, and to surrender his passport. He is scheduled for a preliminary hearing on April 21 at the Dane County Courthouse.
UW-Madison confirmed Kuroda is on administrative leave, with all access to university physical and digital assets revoked. The university said the incident was unrelated to the institute’s virus research, which focuses on influenza and Covid-19, and that no research materials beyond routine laboratory supply chemicals were involved.
