Robert McManus, 21, is accused of spraying bear spray into a home Wednesday night, hitting a woman in the living room who was watching television.
Police say McManus then hopped on the back of a scooter with his friend, Stephen Armbruster, 21, and sprayed bear spray into a crowded fraternity party at the Zeta Beta Tau house next door.
Boulder Police Spokeswoman Kim Kobel says anywhere from 10 to 15 people at the party felt the effects of the bear spray.
"They were vomiting," Kobel said. "Their eyes were watering."
McManus and Armbruster decided to retaliate against someone who stole a painted Greek letter "S" from the Sigma Phi Epsilon fraternity house in the early morning hours of July 4, according to a police report.
Through Facebook pictures, the report says McManus tracked the stolen letter to 955 17th Street, near the CU-Boulder campus.
He and Armbruster rode a scooter to the house, taking a canister of bear spray with them.
"When McManus was confident that 955 17th Street was the 'green house' where the 'S' had been found, he and Armbruster executed their plan," the police report says.
McManus told police he thought no one was home and reached inside the door and let out a spray of the bear attack repellent.
That repellent hit a 19-year-old girl who was watching TV at the time. She felt the spray starting to burn on her arms, and went to a bathroom to call 911, the report says.
Meanwhile, the two friends rode their scooter by a fraternity party next door for nearly an hour, according to eyewitnesses.
McManus then let out another plume of bear spray into the air near the party.
"I got about 15 feet down the sidewalk right there before I got into the pepper spray," Zeta Beta Tau member Beau Radovich said.
Radovich says his eyes watered and his lips started to burn.
"I'd never seen the guys before," Radovich said. "I never heard their names."
Boulder Police Spokeswoman Kim Kobel said the two suspects tried to flee on their scooter, "when the wind shifts and blows the cloud of pepper spray back at them."
That's when police say they crashed their scooter near the fraternity house.
Police arrested McManus on second degree felony assault charges and Armbruster for DUI and accessory to felonies.
Police said both McManus and Armbruster admitted to drinking alcohol before the incident.
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