I don't know much about the geography up there but could someone cross into Canada from that county even if it requires crossing part of Lake Superior? Maybe family or close associates have land there that they wanted to check out? Maybe they found paperwork or documents in the home relating to a location in Ontonagon County? Or a family member in Ontonagon county needed to be notified of what happened? I believe this info was faxed fairly early on so maybe they had info from the home or from questioning family members that made them feel it was important to notify this county?