I think initially when they reported that recording, it contained both the 4th word, and the background noise, but then later, on other sites (like the FBI's site), they had removed both the 'g' sound and the background noise. Obviously LE doesn't want people to consider the g word, for whatever reason, and wants people to only focus on the 3 words........ which, if you knew the person, would likely be enough to raise enough doubt in the mind that it could be that person, that it would prompt the person to make that call. Does it actually matter whether he said 'down the hill', or 'git down the hill', or 'go down the hill', or whatever, I think it all means the same anyway, and unless we can actually identify the perp from the voice and the photo, it doesn't really help us much. jmo and not meaning that to come off as snide!!!! And not directed at the poster above either, but just in general!!
IMO I think there was something on that audio prior to the "down the hill" statement, such as a scream, crying, something that LE didn't want us to hear. The audio seems very carefully snipped.