Unless this is a work related incident and you're working for a government agency that can force you to submit to a polygraph (by firing you or taking other adverse action if you refuse), then I would suggest that you refuse the polygraph. In either case, I think it would be wise to get a lawyer before submitting to any polygraph interrogation.

As for the technique to be used, it would likely be a form of Zone Comparison "Test," regarding which, see Appendix C of the 4th edition of The Lie Behind the Lie Detector. The reference to three questions was no doubt to the number of relevant questions. To these, a number of irrelevant and "control" questions will be added, with the possible addition of a sacrifice relevant and/or symptomatic question. Regarding question types, see Chapter 3 of TLBTLD.

But again, if you stand accused of a crime, my advice would be to refuse the polygraph and get a lawyer. You can then explain that you're refusing the polygraph on your lawyer's advice. If you don't already have a lawyer, Martindale's on-line Lawyer Locator service may be helpful in finding one near you:

http://www.martindale.com