It's a distressingly common trope that engineers don't know how to lie. I fear it's true. Dissembling, subterfuge, misdirection all come hard to the engineering mindset. It's probably even worse for the mathmos. I used to laugh at the 70's sci-fi plots that hinged on our hero using Goedel's Incompleteness Theorem segfaulting the misanthropic computer/robot, but to be honest the average engineer would find it equally difficult to complete their plots of world domination if it entailed stating a bold-faced lie in public.
I recently had occasion to tell my boss Gareth in private something which (for his benefit) he needed to keep quiet for a while. Instead, after coming out of the meeting with me, he dived straight into the office of ueber-boss Paul and remained closeted in there for quarter of an hour. Even a six-year old could have worked out what was going on. My colleague Marc figured out all the essentials of the situation in under five minutes just by watching.
I would be very curious to know if there have been any successful serial killers with an engineering or mathematics degree. The Unabomber only managed to last as long as he did by living away from other people. As soon as he published his manifesto, he was screwed.