didn't do it. >> just as had he with "dateline," edward ates told the jury his version of those computer searches and the trip north a week before paul dunsac's death. but in so doing, he left himself open to the prosecution's cross-examination. >> you had murdered paul dunsac in cold blood, fled that scene driving to your mother's home. isn't that the truth? >> no, sir, that's not true. >> the victim's brother said he listened to ed ates' testimony in utter disbelief. he was praying the jurors had too. >> you knew he was lying. i did not kill paul dunsac. you knew, you just felt he did. >> but it was ed ates' shifting alibi for the crime that the prosecutor believed would undo the florida man. >> when he changed from i was in louisiana on tuesday to i was in louisiana on wednesday, that was