george blumenschein was still suffering, his body ravaged by the toxic chemical ethylene glycol. ging 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 of the brilliant scientists at m.d. anderson were less than chatty. the doctors who you were dealing with are very private people. >> they are, yes. >> reporter: and very intelligent. were they eager, willing witnesses? >> no. >> reporter: did they want to be part of this? >> no one wanted to be a part of this case. >> reporter: still, one of george's closest colleagues made herself available. dr. ana maria gonzalez, george's research partner, the co-worker who was by his side as he checked into the e.r. a fellow workaholic, ana knew the details of george's life at the hospital. how often were they together working? >> seemed like all the time. they traveled together. they worked either in his office or her office. they were always on the phone. >> reporter: dr. gonzalez, who was born in