ORLANDO, Fla. — On an April morning in 2019, federal agents walked into the Tax Collector’s Office in Lake Mary and handed an employee a grand jury subpoena that revealed for the first time that the U.S. Department of Justice was investigating whether Joel Greenberg had used public money to benefit himself. That initial request for records related to Greenberg’s spending and investments was revealed in a plea agreement Greenberg struck with prosecutors which resulted in him pleading guilty to six federal crimes this week and agreeing to cooperate against other potential targets. The deal showe...