A probe into the alleged sabotage of a Puerto Rican beauty queen broadened Wednesday, with police vowing to conduct fresh interviews and pageant officials submitting new evidence to investigators.

Lt. Eddie Hernandez, a San Juan police spokesman, said up to 15 people present at last month's Miss Puerto Rico Universe competition will be questioned in coming days to probe claims of sabotage made by 24-year-old contestant Ingrid Marie Rivera and pageant organizers.

Rivera shocked the U.S. Caribbean territory by alleging that her clothes and makeup were tainted with chemicals, causing her to break out in hives. Pageant director Magali Febles and others say they do not doubt that saboteurs conspired to torpedo her pageant bid.

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But last week, Rivera's evening gown and makeup brush tested negative for pepper spray, forensic experts said, casting doubt on claims that her belongings had been doused with chemicals in a bid to ruin her chances.

Hernandez said polygraph tests may be issued to attendees and pageant organizers who have discussed the alleged sabotage with reporters if the island's Institute of Forensic Sciences does not find traces of caustic chemicals on new evidence submitted by pageant officials, including a swimsuit Rivera wore during a portion of the contest.

A delay of at least four days in submitting the items for testing could have affected the outcome of the forensic tests, according to Abigail Marrero, spokeswoman of the Institute of Forensic Sciences.

Rivera was composed while strutting before judges at the San Juan pageant last month, but backstage stripped off her clothes and applied ice bags to her face and body after she said she swelled up and broke out in hives. She won the crown nonetheless.

Her allegations of beauty pageant backstabbing has attracted worldwide media attention. Rivera recently flew to the U.S. mainland for a round of high-profile interviews on TV programs, including "The Ellen DeGeneres Show."