dr. george bloomenshine was still suffering. his body ravaged by the toxic chemical ethylene glycol. after digging around in his personal life investigators were no closer to figuring out who wanted george dead. so they turned their attention to his professional life. but to the investigators' surprise many brilliant scientists at md anderson were less than chatty. these doctors you are dealing with are very private people? very intelligent? >> yes. >> reporter: were they eager, willing? witnesses? did they want to be part of this? >> no one want to be part of this case. >> reporter: still one of george's closest colleagues made herself available. dr. anna maria gonzalez. george's research partner, the co-worker by his side as he checked into the e.r. a fellow workaholic anna knew the details of george's life at the hospital. >> how often were they together? working? >> seemed like all the time. i mean they traveled together. they worked either in his office or her office. they were on the phone. >> reporter: dr. gonzalez born in colombia, a fast rising star in breast cancer medicine.