An Edmonton man pleaded guilty Thursday to making his boss sick by lacing her coffee with peanut butter.

Kirby Sherick, 27, had been working on the night stocking crew at the Millwoods Town Centre Safeway. Initially, he got along well with his supervisor, Jennifer Evans, when he started the job in December 2010.

By May, the relationship soured after Evans believed Sherick was lying when he repeatedly called in sick for work. Evans started to ignore Sherick at work.

Early in the morning on May 13, 2011, Sherick walked to the nearby Tim Hortons and ordered two coffees — one for him and one for Evans.

According to an agreed statement of facts, Sherick had been warned that Evans was allergic to peanut butter. Sherick obtained a package of peanut butter, scooped out the contents and mixed it into Evans' coffee.

At first, Evans didn't want to take the coffee, but Sherick insisted that it was a peace offering.

About an hour after drinking the coffee, Evans started to vomit and have diarrhea. She went home and felt achiness and flu-like symptoms for the next two or three days.

She had no idea there was peanut butter in the coffee until a month later when an acquaintance of Sherick told Evans' co-worker he had seen Sherick mix in the peanut butter.

"What Kirby did broke my heart.  It shook me to my very soul, everytime I think about it, it makes me so sad," Evans wrote in a victim impact statement.

"It ruined my trust in people."

Sherick pleaded guilty to administering a noxious substance and was sentenced to one year of probation and 150 hours of community service.

He was also ordered to stay away from the store.