Well, this is all speculation.
However, the only reasonably explanation for this situation is that she lied and there is proof that she lied. It is also important to note that she took the 5th during the process. There are really two things that she could have possibly taken the 5th about - - (1) perjury or (2) underage drinking/drugs at the party. I have heard some people argue that maybe she was taking the 5th re: statutory rape, but that seems really unlikely (remember there was an underage recruit who joined in). Because the age of consent in MN is 16, I doubt it would be the statutory rape because you can only take the 5th to avoid self-incrimination (if she had sex with a 17 year old, it could not have incriminated her, so the 5th wouldn't apply).
As far as underage drinking/drugs - - I really doubt that she wouldn't admit to these. They bolster her claim. So it wouldn't make much sense for her to avoid those questions.
I'd guess, and I am pretty confident, that she took the 5th in regards to her lying or making false statements in a police report.
If she made false statements on a police report, she could certainly be liable to damages resulting from those statements.
On a side note, the involvement of the recruit is interesting. If Djam recorded his "turn", that would actually the creation of child pornography. The law is weird, you can sleep with a 17 year old, you can't record it.