Hello, long time lurker, first time posting.
Just a few observations:
Sierra gave her phone number to one of her friends in a twitter post several months back. If someone was stalking her, they can do a reverse phone search and likely be able to find her address.
Also, she tweeted something to the effect of, " Its cold out here, I wish the bus would hurry up", fairly recently. That information would have given a potential stalker the information about what time she generally waited for the bus without having to drive by the area in advance.
I am not convinced it was a stalker necessarily but just throwing that out there.
My last comment is about the man who sierra had "convos" with, and posted screen shots of the conversations.
I was creeped out by the exchanges, especially when he said, "Guess who like you Sierra"?
I tried to find a twitter account with that name, but had no luck. I am certain the name is East Indian, as he appears to be.
I could not find anyone with a matching name, anywhere.
My thoughts on the exchange are based on having been a teenage girl at one point in time.
A. She was either mocking him, or was friendly enough with him that she felt she could play around with him.
B. The fact that she took screen shots of the convos and posted them in her images is something else to consider.
C. He is not listed in her followers, nor is she following him. How they know each other is not apparent.
D. When he says, " How's high school, it comes across as a question from an older person, or someone overseas. (just how it seems to me, no logic behind this really)
E. She gave the description, "Convos with S********h" in her title of the pic, which suggests someone else may know who he is or how she knows him.
None of these things indicate any necessary connection, but are good to consider.