Lt. Jane Doe - S2-E4
Plot hole: It really doesn't make sense that they found the real killer from Jane Doe #1 assuming he also killed Jane Doe #2. They only found him because they assumed he was in prison for the last 10 years. One could explain that he must have gone to prison shortly after the first murder because he said he'd be back but wasn't, but that he was actually recently released is just pure coincidence. And without finding him they would never have suspected Officer Cluxton.
Chosen answer: It is never stated, however she must have been there several years if she is on presidential detail.