Also to note, this incident MyzStery posted about at Lake Kathleen/Renton area - that was March 1st, so presumably he had already met IL by then. It's within the 4-8 week window of "dating" that has been mentioned, so he could have been prowling around the Renton area in that time frame.
I wonder if he (the perp, whoever he is) was looking to steal something from the shed/yard, and the young woman surprised him? The wording "grabbed an xacto knife" is kind of strange. Grabbed it from where? The shed?
Slightly
different description of the encounter here:
http://www.rentonreporter.com/news/370828951.html
"The girl told investigators an unknown man was standing outside as she opened the door at about noon. He grabbed the knife and stabbed her in the stomach.."