[anononaut]

I presume something must have caused you to start giving slightly different questions, right? You did so because you wanted to see if they were collaborating in this fashion.

What was that "something," if you don't mind me asking?

[AmericanBlarney]

I generally like to base my interview questions on the candidate's resume, asking questions of various levels of difficulty about the areas they claim to be skilled. I find it gives a better sense of their abilities than strictly asking about the tools/languages/algorithms being used on the hiring project. As such, each interview was already unique to an extent - and I might have noticed something like a person whiffing the easy questions but then getting an advanced one that didn't add up.

Also, the "architect" I inherited on the team seemed totally incompetent in a variety of ways, and insisted on using a fixed set of questions without deviation. To He kept flagging people through who seemed totally inept when I'd dive into their background, so they was also probably a tip off that they figured him out.