AUSTIN -- Texas prosecutors would be required to test all biological evidence collected at crime scenes for DNA before seeking the death penalty under a bill filed by a Democratic state senator with the backing of the Republican attorney general.The bill, written by Sen. Rodney Ellis, D-Houston, is intended to ensure that only the guilty face execution.He said after-trial DNA testing has reversed 17 death penalty cases in the United States."We always want to avoid the possibility of the wrong person being executed," Ellis said. "We've dodged this bullet a couple of times thanks to advocates for people who have been wrongfully convicted."Ellis said that he does not oppose the death penalty but that the state needs to require testing before a case goes to trial. In two recent cases, exonerations came only after those wrongfully convicted spent more than a decade on Death Row and appeals courts ordered evidence tested for DNA.Attorney General Greg Abbott said he is also concerned about false convictions but added that testing beforehand could shorten the appeals process for those who are guilty."If you are innocent, you will find out your exoneration will come sooner; if you are guilty, justice will be more swift and more certain," he said. While the testing may slow when a trial begins, it is better to take the time beforehand to ensure the police have the right suspect rather than to find out later someone was wrongly convicted, he added.Ellis said he is working on language in the bill that would lay out what evidence police should collect and test and establish what lab performs the tests. The state would pay for all testing, he said.Abbott said there have been fewer than 30 death penalty cases in the last three years, and he does not think the bill will dramatically increase costs. He said that most evidence is tested eventually after a conviction and that mandatory pretrial testing might save money spent on appeals.