prove the negative

"[1] Evidence –Proof of Negative – Sufficiency. Proof of a negative need not be conclusive, but is sufficient when the existence of the negative is made probable or a reasonable presumption of the negative has been created.
. . . The rule is, however, that Full and conclusive proof is not required where a party has the burden of proving a negative, but it is necessary that the proof be at least sufficient to render the existence of the negative probable, or to create a fair and reasonable presumption of the negative until the contrary is shown. (Footnotes omitted.) 30 Am. Jur. 2d Evidence section 1163, at 338 (1967). Accord, 31A C.J.S. Evidence section 112, at 190 (1964); E. Cleary, McCormick’s Handbook of the Law of Evidence section 337, at 786 (2d ed. 1972)." HIGGINS v. SALEWSKY, 17 Wn. App. 207, 210, 211, 212, 213, 562 P.2d 655 (March 28, 1977).