SDCL § 43-41-8: Sale by finder of thing found.

The finder of a thing may sell it if it is a thing which is commonly the subject of sale, when the owner cannot with reasonable diligence be found; or being found, refuses upon demand to pay the lawful charges of the finder, in the following cases:

(1) When the thing is in danger of perishing or of losing the greater part of its value; or

(2) When the lawful charges of the finder amount to two-thirds of its value.