Aren't You Glad You Didn't Turn On The Light?

The legend I decided to base my project on was "Aren't You Glad You Didn't Turn On The Light" which in short describes how a girl returns from a party and decides not to turn on the light to save waking up her flatmate. When she does to wake her flatmate in the morning she discovers that she is dead and the message "Aren't you glad you didn't turn on the lights!" is written in her blood. 

Here is the legend in full:


"Two dormmates in college were in the same science class. The teacher had just reminded them about the midterm the next day when one dormmate — let's call her Juli — got asked to this big bash by the hottest guy in school. The other dormmate, Meg, had pretty much no interest in going and, being a diligent student, she took notes on what the midterm was about. After the entire period of flirting with her date, Juli was totally unprepared for her test, while Meg was completely prepared for a major study date with her books.
At the end of the day, Juli spent hours getting ready for the party while Meg started studying. Juli tried to get Meg to go, but she was insistent that she would study and pass the test. The girls were rather close and Juli didn't like leaving Meg alone to be bored while she was out having a blast. Juli finally gave up, using the excuse that she would cram in homeroom the next day.
Juli went to the party and had the time of her life with her date. She headed back to the dorm around 2 a.m. and decided not to wake Meg. She went to bed nervous about the midterm and decided she would wake up early to ask Meg for help.
She woke up and went to wake Meg. Meg was lying on her stomach, apparently sound asleep. Juli rolled Meg over to reveal Meg's terrified face. Juli, concerned, turned on the desk lamp. Meg's study stuff was still open and had blood all over it. Meg had been slaughtered. Juli, in horror, fell to the floor and looked up to see, written on the wall in Meg's blood: "Aren't you glad you didn't turn on the lights!""

From reading this there is a number of things that we can infer. Juli was present when the murder took place, or arrived after but while the murderer was still there, hence the message written in blood. Also the murderer most likely had a specific grudge on Meg and only wanted to kill her, mean they were probably close. Or perhaps the murderer wanted to mess with Juli's dead, by leaving her living and writing the message in blood, so maybe Meg was the true victim?

These are just a few ways in which the text can be interpreted, so it is up to me to decide how I want the story to play out.

References:
http://urbanlegends.about.com/od/horrors/a/turn_on_light.htm