Hate to sound so negative why waste money or time on this issue.Would rather spend my money on the guns and ammo we will all soon need to survive when the police can no longer help Sorry to sound so negative. Sad to see this hobby die.
There are plenty of federal, state & local LE personnel who out of stress in the heat of a situation or plain ignorance/stupidity, say sensitive things on non-secure channels. I've pretty much given-up trying to educate them about OPSEC/COMSEC, and instead, tend to push towards encryption to give a level of protection to their operations.
One thing to keep in mind is even if they were willing to give you the encryption keys, they may not even know them. If they are in an otar environment, the system automatically generates keys and pushes them to the subscribers. They could have the system set to roll the keys every day if they wanted (typically it's once a month or so). .
As for the recordings, what may have hurt you was requesting 3 years worth. In fl we were allowed to charge labor fees and I can tell you three years worth of encrypted audio would be expensive. I am not even sure if we kept 3 years. I would have to go back and look at the statutes.
That's one of at least two lawsuits now. I filed one this afternoon as well. Although I'm challenging a different aspect; Little Rock police even denies access to recordings through Freedom of Information Act requests. Here are the complete documents of the suit: http://jaunty-electronics.com/blog/wp-content/uploads/2014/08/Sebastian_vs_LRPD_et_al.pdf