The man was careful to cover his tracks, erasing e-mail messages and other incriminating documents. He sent especially sensitive messages to his prospective employer via a Web-based e-mail service, not the corporate e-mail system of his current employer. And with good reason: The man had landed his new position by promising he’d bring trade secrets from his former job. Unfortunately, the former employer didn’t suspect anything until months after the rogue employee had left. By then, his PC had been erased and given to another employee. The prospects of finding evidence of suspected wrongdoing seemed bleak. But forensic investigators at Huron Consulting Services LLC in Chicago had a few tricks up their sleeves…