As it stands, arrests aren't going to get Brazil what it wants. Police have been demanding WhatsApp messages that Facebook says it not only doesn't keep, but are encrypted end-to-end. The firm wouldn't have much luck producing usable info even if the chat records fell into its lap. So long as it's telling the truth, investigators may have to simply accept that the evidence is unavailable, and that no amount of imprisonment is going to make it show up.