Police say surveillance video shows a man who may be behind four sexual assaults on women in three towns.
The attacks date back to Nov. 2010. In each incident, the attacker assaulted the women in the middle of the night.
"What's worst is it's happening in the one place that they feel the safest and that is in their own home," said one police officer.
All the victims are African-American women in their 50s and 60s. And all of them are alumni of the Delta Sigma Theta Sorority, an organization of more than 250,000 predominately Black women.
Police say during each assault, the suspect revealed he knew personal details about his victim.
Authorities said that the suspect is described as a large, heavily built black man in his late 30s to mid-40s, around 250 to 300 pounds.
Police wouldn't say how the suspect is gaining entrance to the homes, but have offered home safety checks to the sorority's alumni members.
Delta Sigma Theta wrote an email to local chapter alumni: "This is frightening to all and somewhat unbelievable that our sisterhood is being attacked in this manner."
They went on to say that they are "aggressively gathering information to distribute to the chapters."
ABC News contributed to this story.