Circumstance from Google/Oxford
1. a fact or condition connected with or relevant to an event or action.
"we wanted to marry but circumstances didn't permit"
- an event or fact that causes or helps to cause something to happen, typically something undesirable.
So Monday, Feb 13th was an unusually warm winter day and a day off school. After a sleepover at Libby’s place, the two girls asked to spend the afternoon at the bridge, hiking and taking photos. Although they had no means to get there on their own, Libby’s sister kindly agreed to drop them off on her way to her boyfriends place. They arrived just after 1:30pm.
This to me all that describes the “circumstances” (ie situation) causing them to be at the bridge at the exact same time a killer was lurking.
Had the weather not been warm, had they been in school, had the two friends not been hanging out together, had they not went to the trail/bridge but instead to somewhere else, etc this tragedy wouldn’t have occurred however there easily might’ve been different victim/s .....but still totally opposite to that of a targeted murder, premeditated murder of Abby and Libby.
JMO