Owl to Severus Snape ((Charmed readable only to Snape, and dissolving into a blank page after its read.)) Snape, I know it was you who let us out. I don't know why. But if you really want to help, then prove it.
We need hairs from the Lestranges. If you can do it, then send it to McGonagall, and she'll send it to us. If not, then I'm going to assume whatever reasons you had for letting us out, it wasn't to actually help us.