I think she was hiding something pretty bad, as this is A LOT of effort to disappear... The North Hollywood Police, 402 months thing might be not for her, but someone else. Maybe her father went to prison for 402 months, or a boyfriend, or something. Maybe she committed a crime with an accomplice, who was caught and she wasn't. The accomplice went away for 402 months, and Jane Doe is scared she'll get ratted out, so she flees and creates a new identity? Just brain storming. Then again, the 402 months doesn't seem necessarily related to the North Hollywood police thing. Maybe it's been 402 months since something important happened? 402 months is a bit over 33 years, so it's not how long she's had the false identity. If this note was written in 2010, 402 months ago was sometime in 1977. Maybe that was when she first left "home" and the people she knew before? Or maybe before she was Lori and Becky Sue, she had another identity, that she took up in 1977. Maybe not one with documents and all, but something other than her real self that she was going as.