The history of the use of 'truth-serum'

Scientific American - What is truth serum?

A short article without a lot of science, giving the history of the sodium pentothal and other barbiturates that were once used in medicine. The first doctor to document things like this was looking at scopolamine, or 'twilight sleep', which seemed to put patients in a mood to give answers without having to think about them. He first envisioned its use not to extract guilt but instead to confirm people were telling the truth about their alibis. Doctors in WWII would use sodium pentothal as a therapy-- soldiers who had been injured and lost the ability to speak or remember would have a better time of it under the drug. In general, there is a lot of skepticism about the veracity of the things that come from a person's mouth while under the drug-- those drugged are also very suggestible and quite willing to say what they think the interviewer wants to hear.