By TMZ Sports
Former three division world champion "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 New York 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 Shane presented the divorce document in court last week in Los Angeles... in hopes of getting a judge to freeze Jin's assets.
TMZ broke the story ... Shane's hoping to get back all or some of the cash and assets he forked over to her when they divorced -- since they were never really married, he believes.
As part of the divorce, he forked over:
- Three houses
- Several investment and bank accounts
- 2009 Mercedes G Wagon and 2008 Cadillac Escalade
- Income from Mosley's fight library
- $600,000 lump sum for spousal support
We're told the judge has not ruled yet on Shane's request.
Jin has not returned our calls for comment.