>>Investigators linked Shaun Earl Arender, who was already in jail on burglary and drug possession charges unrelated to the murder, to the crime scene with DNA evidence from Hannah’s shirt, according to Navarro County Sheriff’s Chief Deputy Mike Cox.<<
From here
http://www.postchronicle.com/news/original/article_212106304.shtml
According to this report the affidavit says “possible match”