A Baltimore law firm lost a portable hard drive containing information about its cases, including medical records for 161 stent patients suing cardiologist Dr. Mark G. Midei, a firm client, for alleged malpractice at St. Joseph Medical Center in Towson. The drive was lost Aug. 4 by an employee of Baxter, Baker, Sidle, Conn & Jones who was traveling on the Baltimore light rail, according to a letter obtained by The Baltimore Sun that was sent to one of the stent patients last week -- two months after the drive went missing. The storage device held a complete back-up copy of the firm's data, including medical records related to the stent malpractice claims, along with patient names, addresses, dates of birth, social security numbers and insurance information. It was taken home nightly as a security precaution in case of fire or flood, a firm spokesman said, though the portable information was not encrypted -- among the most stringent security precautions that is standard practice for health professionals dealing with medical records.