HOUSTON -

Some patients treated by the Harris County Hospital District may have had their personal information stolen, district officials said Thursday.

Hospital district officials said a now former employee may have stolen patients' information, including their names, addresses, telephone numbers, dates of birth, Social Security numbers, medical record numbers, emergency contact information, payer information and information about the care they received.

The information, as far as is known, was stolen in an attempt to defraud Medicare, not patients, hospital district officials said.

Officials said they do not know how many patients' information was misused. Letters have been mailed to patients whose information was accessed by the employee, officials said. The hospital district has offered 12 months of ID theft recovery services to those patients at no charge.

Hospital district officials said they believe the information was stolen from April 14, 2008 through Feb. 11, 2011. The former employee has been indicted on federal charges and is set to go to trial later this year.