My own unfounded suspicion is that the perpetrator was a stalker, someone attracted to or even obsessed with Carolyn. Not a boyfriend or ex, but someone on the periphery of her social circle. Part of her circle would have come from her volunteering in the community.
She was very engaged in charitable activities according to her family. Her mother said as much in requesting donations to the Children's Brain Tumor Project at Weill Cornell Medicine:
“We want the last chapter of Carolyn’s life to be one where her friends and loved ones can help others in her memory. Carolyn was a true philanthropist who was active in many charitable organizations, and we know she would have wanted to help other children under Dr. Souweidane’s care by supporting his research,” said Carolyn’s mother, Jennifer Byington.
Donate in memory of Carolyn Byington - Children's Brain Tumor Project
Her obituary states: "As an avid volunteer, Carolyn was active in the Junior League of Greater Princeton." The Junior League is a woman's philanthropic organization. They promote academic enrichment, health, and wellness for children and support underprivileged women in Trenton.
This annual report from 2018 from the Junior League of Greater Princeton has Carolyn listed as one of their donors that year (see page 10 on the following link):
THANK YOU TO OUR GENEROUS DONORS! Gifts and in-kind donations made between June 1, 2017 and May 31, 2018
https://www.jlgp.org/wp-content/uploads/2018-Annual-Report-FINAL2.pdf
A few years previous, presumably before she moved to Plainsboro and around the time she graduated from Lafayette College, Carolyn joined her mother Jennifer in support of a similar woman-led philanthropic group called Impact 100 Garden State. If you scroll down to page 3 in the following page, you'll see a photo of Carolyn and her mother:
https://impact100gardenstate.org/wp-content/uploads/2016/03/Newsletter.Summer-Edition.pdf
So, Carolyn was quite involved in charitable activities, particularly organizations for women, and was following in her family's footsteps in being engaged in the community. She graduated from Lafayette having double-majored in international affairs/anthropology and sociology. She studied abroad in Germany and Japan. You get the picture of a very idealistic and ambitious young woman dedicated to improving her community and the world.
But what if it was through these charitable activities that she came to the attention of her assailant?