A University of Wisconsin–Madison lab researcher, Makoto Kuroda, was arrested after allegedly adding toxic chemicals to a coworker’s water bottle and shoes.

The coworker noticed a strange odor and chemical taste in the water, which tests later confirmed contained chloroform.

Investigators say Kuroda admitted he acted out of anger over a workplace promotion and rule disagreements.

He also reportedly wanted to make the coworker sick and used lab-related chemicals that can be dangerous if ingested, the Daily Cardinal has reported.

Kuroda faces reckless endangerment charges and is awaiting a court hearing.