WEST PALM BEACH, Fla. (AP) – The FBI and the U.S. Postal Service have joined the criminal investigation into the disclosure of the names and addresses of some of the 6,500 HIV/AIDS patients in Palm Beach County.

County Health Department Director Dr. Jean Malecki said the FBI and postal inspectors have joined the police probe of two incidents in which a confidential list of names of those with AIDS or who are HIV-positive may have been used illegally.

Florida requires people who carry HIV to register for monitoring purposes. Disclosing the list is a crime.

A confidential list of about 6,500 HIV carriers was mistakenly emailed to about 800 county health workers in February. At least 16 people opened the email. The list did not include addresses.

In early March, HIV-positive people on the county health department list received letters telling them to call an Indiana company to volunteer to help local families dealing with AIDS.

One letter said, “Your name appeared on a list of HIV-AIDS patients for Palm Beach County.”

The Indiana company, which does electronic billing for doctors’ offices, had no knowledge of the letter and told callers to contact the health department.

Malecki and other health officials have said they do not believe the mailing letters came from the emailed list because the original did not include addresses.

“The FBI and U.S. Postal inspectors have the resources to trace DNA on the envelopes from this mailing,” Malecki said. “We’re hopeful that they can find out who did this. It’s really a despicable crime and has terrorized some of the people on the list.”

Another investigation by the state Health Department’s inspector general into the original emailing of the list continues, Malecki said.