There was a great article in the New Yorker about police interrogation techniques and how they can influence people to confess to crimes (and the studies that explain why people would falsely confess).
This is probably the most important point I remember from "The Demon-Haunted World", in which Carl Sagan repeatedly demonstrates that human memory is completely unreliable, and that false memories can even be accidentally created by a therapist. People who say they've been abducted by aliens usually aren't lying; they genuinely believe it.
There's also this article: [The Reykjavik Confessions – The mystery of why six people admitted roles in two murders - when they couldn't remember anything about the crimes.](http://www.bbc.com/news/special/2014/newsspec_7617/index.htm...)
It gives a great inside how the investigation may have affected the suspects.