You can get local Child Support contact info at
http://childsupport.wisconsin.gov. Unfortunately, the only direct contact info I have is for a different county. If you're pretty certain he's in Middleton, you'll want to use the Dane County contact info.
If he's a legal resident in
WI now, you can bring a case through the Child Support agency (
WI SCTF) with the result that Wisconsin would directly attach part of his paychecks and all of his tax return (inc. the state return that Ohio can't touch while he's here) and then send it on to Ohio. I'm not sure what's involved with that specifically, but I pay child support through
WI (where I got my divorce and offered to pay support) to Oregon, where my ex lives with our son, so I know the necessary bureaucracy is there. Your caseworker and whomever you contact in Dane Cty. could give you more info on that.
I agree with Rob on the suggestion for contacting the Middleton police, too. Except I believe you have to do it through your local police where he's wanted, and then they request that he's arrested here and transfered to Ohio. Every state has different laws on that though.
I really hate deadbeat parents. The obvious issues aside, they make it really tough for those of us who are NOT deadbeats but who don't have their children living with them. The laws get stricter and stricter around it, but as far as I can see, they only people the stricter laws are affecting are those of us who pay our support and follow the law already anyway.
Good luck!