The Surgeons of Lake County, located in the affluent northern Illinois suburb of Libertyville, revealed last month that hackers had burrowed deeply into its computer network, infiltrating a server where e-mails and electronic medical records were stored. The Surgeons of Lake County isn't the first healthcare provider to be targeted by extortionists. But the incident, which was spotted by privacy blogger Dissent Doe in a federal database of health-related breaches, showcases an unsettling new strain of opportunism that is emerging as criminals try to exploit the industry's shift to digital medical records.