The solution for this, along with most interviewing problems, is to get your team together and come up with a very clear picture of what it is that you're looking for in a candidate. Hash it out and write it down. Now take that list and write out a group of questions that help to suss out whether or not the candidate has those things. Use the same group of questions for everyone that you interview for that position. Nothing good comes from asking gotcha questions. It's more likely to happen if you don't have a clear, documented process.
Depending on what your needs are, you may need to do a technical interview. Do the same thing with the technical interview, figure out your needs then write your questions. Have a similar group of people doing the situational interviews do the technical interview, preferably the people the candidate is going to work with. Find a way to make it collaborative if you can. Seeing how a candidate works with other people is nearly as valuable as seeing how technically proficient a candidate is.
Depending on what your needs are, you may need to do a technical interview. Do the same thing with the technical interview, figure out your needs then write your questions. Have a similar group of people doing the situational interviews do the technical interview, preferably the people the candidate is going to work with. Find a way to make it collaborative if you can. Seeing how a candidate works with other people is nearly as valuable as seeing how technically proficient a candidate is.
That's it.