Where can I find the the SQLite binary SQLite.Interop.dll?

There are supposed to be an x86 and an x64 version of the library SQLite.Interop.dll so that you can work on either machine architecture. However I cannot find where this binary comes from. I've downloaded the .NET 4.0 precompiled binary packages from system.data.sqlite.org (both statically-linked and non), and they just aren't in the zip packages. I don't get it. They are referenced several places in the documentation yet they are not provided in the downloads.