Surveillance photos have been released of the renowned Texas cardiologist killed in broad daylight as he rode his bike to the hospital Friday in the hopes of identifying the suspect. Dr. Mark Hausknecht, who treated President George H.W. Bush, was gunned down by another man on a bike. A surveillance camera aboard a bus in Houston captured video of the doctor crossing an intersection over the weekend. As the doctor goes out of frame, the suspected killer comes into view about a half block behind him.