What is the test for finding probable cause for the forfeiture of a property de novo?

We review a district court's determination of the existence of probable cause for the forfeiture of property de novo. United States v. Padilla, 888 F.2d 642, 643 (9th Cir.1989). In civil forfeiture proceedings, a grant of summary judgment "must necessarily be construed in light of the statutory law of forfeitures." See United States v. One 56-foot Yacht Named the Tahuna, 702 F.2d 1276, 1281 (9th Cir.1983) (quotation omitted). In such proceedings, the government bears the initial burden of showing probable cause to believe that the property seized was the proceeds of a narcotics violation or was used to facilitate such a violation. See Padilla, 888 F.2d at 643. The burden of proof then shifts to the claimant to show by a preponderance of the evidence that the property was not involved in a narcotics violation. Id. at 645.