It is possible D texted the friends that allegedly came over in the morning and called the police. Given they're students and it was late she may not have received a reply because people were drunk/high/sleeping
Though if she didn't think to text other housemates just to check if they're okay, especially as she had heard them possibly awake, then I'm still very confused about what was going through her head
One of the rumours, which also seems to have some local origin to it, is that she was high at the time. If that's the case people don't expect her to be able to give evidence in court