"Sugar" Shane Mosley firmly believes his ex-wife was married to another man at the same time as him ... because he has papers nailing down the date she divorced the guy.
Sources close to Mosley tell TMZ Sports ... Shane's lawyers obtained a NY State Certificate of Dissolution of Marriage for Jin Mosley, dated Sept. 26, 2006. Shane and Jin were married from 2002 to 2011.
Do the math ... it all adds up to bigamy, as far as Shane's concerned.
We're told the judge has not ruled yet on Shane's request.
Jin has not returned our calls for comment.
Article Courtesy of TMZ Sports