Cleveland Cavalier owner Dan Gilbert has hired a high-powered law firm to conduct an extensive investigation into whether the Miami Heat violated league rules by having illicit contact with LeBron James before he became a free agent.

Gilbert has invested several hundred thousand dollars into building a case against the Heat, with the intent of submitting compelling evidence of tampering to the NBA league office.

A source said the Cavs are "determined to get everything out there. They’re not letting go of this. They’re not going to just let this die."