Before a ballot is accepted for counting, the signature on the returned ballot envelope is compared to the signature(s) the County has on file for the voter to ensure the signatures match.
Elections staff performing this work are routinely trained in signature comparison techniques by current or former members of the Washington State Patrol who specialize in forensic handwriting analysis.
Signatures that do not match are flagged as challenged for second and, if appropriate, third review by senior staff. Flagged signature issues are not a sign of fraud. Signatures may be flagged as the result of a signature evolving over time, another member of the same household accidentally signing the wrong ballot envelope, or a voter forgetting to sign the ballot envelope entirely.
If a ballot is flagged as challenged, the voter is contacted and provided an opportunity to resolve the issue with their signature.