We can't say what they did or will do in the future. The trial hasn't begun yet. That's when we'll learn what LE has done. Right now, its just gossip and guessing. JMO
There's also a legal process that LE has to follow in order to hire experts, have them examine evidence, etc. No, they're not allowed to have experts sign non-disclosure agreements. They're actually required to testify in court and explain their work and how they reached their conclusions. They're familiar with the process, the law, etc.