Police said the adult male smeared his excrement in the bathrooms, then took off his shirt and tried to stuff it in a toilet.
A passenger, Tricia Mason, said the man was "shaking the seats all around him... [and] pouring soda and water on the floor and on laptops."
"Something wasn't right with him upstairs," passenger BJ Canup told KTVA's Scott Gross. "I saw him spreading feces on the bathroom wall with his shirt. He was pouring soda and spitting food all over too"
While the man's identity has not been released, Gross reported that the man was released from jail in Evansville, Indiana two days before the flight.
His family bought him a one-way ticket to Vietnam, where he was going to live with other members of his family. He previously lived in Oakland, California and is 22 years old.
The man that caused chaos on @United flight from #Chicago to #Hongkong was released from jail in Evansville, IN 2 days prior. Fam bought him a #oneway ticket to #Vietnam to live with family. The man is 21-22 years old and lived in Oakland, CA before living with aunt in IN. @ktva— SCOTT GROSS (@11ScottGross) January 5, 2018
The man was cooperative with police when the plane landed. KTVA reports that he was interviewed by the FBI and Airport Police. He was taken to a nearby hospital for a psych evaluation. He has not been charged yet, but the FBI is investigation.
Tri Nquyen, who sat next to the man, told KTVA that the man's aunt in Evansville wanted him to keep an eye on him.
"His mom lives in Oakland, California, and he just kept getting into trouble," Nquyen told KTVA. "So he was moved to Evansville to live with his aunt where it was believed a change of scenery would help him. It didn't work, he's been in trouble for the past five years."
Despite the inconvenience, the passengers had nothing but praise for the United crew. They stayed at a hotel in Anchorage and their flight was rescheduled for Friday.