DALLAS (AP) -

The recent case of a Texas man convicted of tax fraud highlights a lucrative black market for stolen personal information the IRS estimates costs U.S. taxpayers more than $6 billion a year.

Luigi Montes was sentenced last year to five years in prison for organizing a scheme to steal the identities of Puerto Ricans to file bogus tax returns and receive refund checks.
    
The Dallas Morning News reported residents of Puerto Rico have Social Security numbers but aren't required to pay federal income taxes unless their employer is based in the U.S. This makes it more difficult for authorities to track fraudulent tax returns.
    
More than 140 returns and the personal information of others were found at homes tied to Montes in Houston and the Dallas suburb of Balch Springs.