About 531,000 people who had records in a state agency’s hacked prescription-monitoring database will receive letters this week advising them to keep close watch on their credit record. The Virginia Department of Health Professions issued similar advice last month after the hacking of the Internet-accessed database surfaced April 30 but now is notifying people individually to take precautions.

The FBI has not discovered the hacker who broke into the Virginia Department of Health Professions’ computer, nor has it discovered what private information was retrieved, Virginia’s Secretary of Health and Human Resources Marilyn B. Tavenner said yesterday. Questioned intensely by members of the House Appropriations Committee, Tavenner said the FBI believes it will take another two weeks to complete its investigation.

Virginia Health Professions officials said they don’t have any evidence that personal information was stolen by hackers who accessed a Web site that collects data on some patient prescriptions. Nonetheless, the department is advising patients and providers who may have data in Prescription Monitoring Program files to be extra vigilant over the next 12 to 24 months in reviewing their financial statements and credit reports.

State and federal authorities are investigating a possible extortion demand that seeks $10 million for the safe return of more than 8 million patient records and 35 million prescription records that allegedly were hacked last week from the Virginia Department of Health Professions computers. An extortion note posted on WikiLeaks, a Web site that publishes anonymous submissions and leaks of sensitive government and corporate information, reads:

Hackers may have infiltrated computers containing licensing information on doctors, nurses and other professions overseen by the Virginia Department of Health Professions. By yesterday afternoon, all 36 computer servers storing the state agency’s records were shut down after a midday message popped up on some computer screens that implied the system was being hacked.