Guilty by inference. What happened to a beyond a shadow of doubt. It doesn't sound like they could prove anything.
...
Fortunately or unfortunately, "Since the enactment of the Civil Asset Forfeiture Reform Act of 2000, the burden is on the government to establish, by a preponderance of the evidence, that seized property is subject to forfeiture."
So, the Eighth Circuit "[concluded] that the government proved by a preponderance of the evidence that the defendant currency was substantially connected to a narcotics offense."
I'm no lawyer, but it seems that "preponderance" is not a particularly high legal standard, not on the same level as proof or probable cause...perhaps "preposterous" would be a better word, I dunno. It is what it is, act accordingly.