You know, this is very disturbing given the recent rape and murder of another female jogger in daylight.
I was a competitive runner for over a decade and still log a fair number of miles. Although cases of lone joggers being attacked weren't totally unheard of, they were very rare and murders were rarer still. The running world subculture is very closely knit and word travels fast regardless of what type of attack occurred and in what city. It's very unsettling that these two episodes happened so recently to each other. There's thousands upon thousands of runners who train alone (or else they'd be unable to train at all or in a very limited way) and most of us have never had a reason to fear for our safety. Honestly, the biggest threats to runners are cars and the occasional vicious dog. It's probably far more likely that a runner who is afraid to venture out alone on the streets has a much higher chance of dying in an auto accident on the way to or from a gym.
It could be a coincidence that there are two different random predators who struck in broad daylight (and probably is, given the distance between the two murders) but it does seem odd that both women were from NYC and had active social media accounts.