SAN JUAN, Puerto Rico (AP) — Pepper spray failed to deter Ingrid Marie Rivera, who beat 29 rivals to become the island's 2008 Miss Universe contestant.Pageant organizers said they hope to catch and expose whoever was responsible for dousing Rivera's evening gowns with pepper spray and spiking her makeup, causing her to break out in hives.Police said Monday they have also opened an investigation into the attacks on the beauty queen.Rivera was composed while appearing before cameras and judges throughout the competition. But once backstage, she had to strip off her clothes and apply ice bags to her face and body, which swelled and broke out in hives twice."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."Rivera's clothing and makeup later tested positive for pepper spray.Someone also stole Rivera's bag containing her gowns, makeup and credit cards. And a bomb threat forced pageant officials to postpone the last day of competition on Thursday, said Magali Febles, director of the Miss Puerto Rico Universe pageantAuthorities said they searched with dogs and didn't find any explosives.A tearful Rivera recounted her ordeal at a news conference Sunday, acknowledging she had wavered about staying in the contest."At one point I said, `Am I a masochist?'" she recalled, her voice breaking. "But I said, `I am with God and this is my goal, regardless of the results.'"Beauty competitions in the U.S. Caribbean territory — which boasts five Miss Universe titles, second only to the U.S. — are fierce, drawing boisterous audiences and accusations of rigged results.But the pranks under investigation this year are a first, Rosario said.Rivera, who won Miss World Caribbean in 2005, had been a target of controversy from the start of competition, as rivals complained she was too experienced and should be disqualified.Local media touted her as the likely winner, stoking jealousy among contestants, Rosario said.When Rivera won, rivals accused her of buying the crown, Puerto Rico's El Nuevo Dia newspaper reported.