Surveillance video shows Tanis Ukena hovering over the cup for a longer-than-normal time, police said.
Police arrested Ukena. They say they believe that it is an isolated incident.
Ukena was charged withsuspicion of surreptitious administration of a poisonous substance, The Salt Lake Tribune reported.
The officer was released from the hospital and is taking a few days at home to recover, KSL reported.
Police are investigating whether the sergeant was targeted because he is in law enforcement. He was in uniform and was driving a cruiser, The Tribune reported.