Is there Mail in Ballot Fraud in Fort Worth's District 8?

Take a look at the high number of mail in ballots for District 8 & District 5 in Ft. Worth http://tcweb.tarrantcounty.com/evote/cwp/view.asp?a=770&q=471950. Scroll down near bottom of the page and click on mail in ballot roster for the respective Council Districts, you'll see that most of the mail in ballots come from the zip codes of predominantly black areas of the Districts. WHY?

"Rep. Rafael Anchia, D-Dallas, revisited his conclusion after years of testimony that there have been no cases of in-person voter impersonation in Texas. A bigger problem, Anchia suggested, is likely fraud by individuals abusing mail-in ballots."

http://www.statesman.com/blogs/content/shared-gen/blogs/austin/politics/entries/2009/04/06/legislators_frame_voter_id_hea.html

http://www.voterlaw.com/media09172006.htm

http://tcweb.tarrantcounty.com/evote/lib/evote/forms/BBM_assistance.pdf