My fiance married a woman in Panama 20 yrs ago. Never lived together, she never came here, and no contact in @10 yrs. How can he divorce her?

Jurisdiction for divorce is established by residency in the state where you are now living, not where you were married. If you reside here in Wisconsin, you must be a resident of the state for 6 consecutive months and the county you live in for 30 days prior to filing. If you meet that requirement, you csnnfild for divorce. You will need to hire a process server prvsheroff to personally serve the divorce papers on your spouse. If they can't be found, after reasonable attempts have been made to have the papers served, you can resort to what is called, "substituted service." This allows mailing the pairs and publishing in the newspaper. Once all of that is accomplished and assuming no response from your spouse, you should be able to proceed with a default divorce in Wisconsin.