There are VERY few agencies still using the old inversion scrambling, which is the only method of encryption possible to unscramble.
Law enforcement scrambling now is digital, and not possible (short of NSA grade equipment and personel) to decode. Yes, there is in theory a possibility that you might, in time (weeks or months) decode DVP... but not from a streamed audio feed. You have to have the original transmission recorded at high quality to hope to do that.
The only place I've heard inversion scrambling on in 10 years now is GMRS bubblepack radios.