SAN JUAN, Puerto Rico (AP) – Federal authorities hunted for nine suspects Friday amid an operation against dozens of “doctors” accused of obtaining their licenses through fraud – and the father of one of them allegedly threatened to kill anyone who cooperated with investigators.

Gilberto Rodriguez, who is himself a doctor, was jailed on a witness tampering charge.

A notice taped to the door of his shuttered medical practice in a San Juan strip mall said he was away “on vacation” until Monday.

A federal grand jury on Wednesday indicted 91 people, including a former director and a secretary of the licensing board and Rodriguez.

A total of 88 people were accused of having obtained medical credentials by fraud.

Among the nine still being sought, three were believed to be in Puerto Rico and five in Philadelphia, Florida and in the Dominican Republic, said Assistant U.S. Attorney Jose Ruiz.

Ruiz said the probe could produce charges against more people.

One of the doctors, Arcelio Torres, is a reportedly a plastic surgeon to local celebrities. He previously boasted of treating the acne of Denise Quinones, before she was crowned Miss Puerto Rico and then Miss Universe in 2001.

A government official who serves as a patients’ advocate appealed for calm as rattled islanders checked their doctors’ qualifications.

“The accusations against these doctors have grave implications for the health and lives of the patients treated by these professionals,” Luz Teresa Amador said.

The doctors allegedly flunked their certification exams – more than a dozen times in some cases – and had their results falsified. Members of the island’s medical licensing board allegedly recycled old, passing exams under the name of the failed candidates between 2001 and 2005, according to the indictments.

Patterns of repeated test scores suggest the cheating began much earlier than first suspected, Ruiz told The Associated Press.

“It was a pretty blatant scheme,” said Ruiz, who added that investigators were trying to locate rosters from before 2001. “We believe this has happened before.”

Some of the doctors gave board members gifts or cash payments of as much as $10,000, but others had their scores changed for free, according to the indictment.

About 60 percent of the defendants are Puerto Rican, and the vast majority received medical training overseas in countries including the Dominican Republic, Mexico and Cuba. At least 75 were practicing medicine in Puerto Rico, authorities said.

Ruiz said authorities would focus on gleaning information from the doctors already indicted and that more arrests are likely in a few weeks. The defendants face charges including mail fraud and making false statements to Medicare and, if convicted, face prison sentences of five to 20 years.

The Caribbean territory’s licensing board said states including Florida, New York and Texas recognize Puerto Rican medical licenses, but the local Health Department said none of the suspects were known to have practiced medicine on the U.S. mainland.

AP-ES-08-03-07 1925EDT