Organisers of a beauty pageant in Puerto Rico are investigating a case of sabotage after a contestant's dress and make-up were covered with pepper spray.
Ms Rivera won Miss World Caribbean in 2005
Ingrid Marie Rivera beat 29 pageant rivals to become the 2008 Miss Universe contestant, despite breaking out twice in hives - a red swollen rash.
Ms Rivera remained composed onstage before the judges, but backstage she applied ice packs to her face and body.
Her clothing and make-up later tested positive for pepper spray.
"We thought at first it was an allergic reaction, or maybe nerves," said pageant spokesman Harold Rosario.
"But the second time, we knew it couldn't have been a coincidence."
The pageant organisers said they hoped to catch whoever was responsible for the prank but have not involved the police.
The pageant also saw the theft of Ms Rivera's bag - which contained her dresses, make-up and credit cards - and the last day of the competition was postponed after a bomb threat.
Ms Rivera admitted that she had considered dropping out of the contest. "At one point I said, 'Am I a masochist?'"
"But I said: 'I am with God and this is my goal, regardless of the results.'"
Ms Rivera won Miss World Caribbean in 2005, and local media had predicted she would win the Puerto Rican pageant.
Her rivals complained she was too experienced and should be disqualified.