Texas police were searching for a serial rapist who appears to be targeting sorority sisters after he broke into the homes of four women in their 50s and 60s and attacked them.
The violent assaults by what police believe is the same massive man have sent shockwaves of fear through the Delta Sigma Theta community - the largest historically black sorority in the United States.
None of the women - who went to different colleges - knew each other or their assailant.
But he told his victims that he knew a fair bit of personal information about them.
"To think that our members are being targeted is disturbing and extremely disheartening," Cynthia Butler-McIntyre, national president of Delta Sigma Theta, said in a statement.
"We encourage members to be alert, remain aware of their surroundings and to call the police if they see anything suspicious or feel threatened."
The sorority urged its alumni to remove sorority paraphernalia from their vehicles, key chains, homes, offices, refrain from wearing clothing or accessories that identify them as members, remove personal information including day-to-day whereabouts from social media, and "avoid going out or staying home alone."
The first assault was in November. By the time the second woman was attacked in April, police were worried they might have a serial rapist on their hands.
The third woman was assaulted in September and the fourth earlier this month.
They were all attacked when they were alone in their homes and the assaults took place between the hours of 9:00 pm and 4:00 am.
Police are hopeful that a newly-released surveillance video will help them track down the rapist, who was described as a black male in his late 30s to mid 40s, somewhere between 5'7 and 6'0, 250-300 pounds.
"Somebody knows this guy," said Heather Bowden, a spokeswoman for the Plano, Texas police department.
"The video - you can see how he walks, the stance. I'm hoping that now that we've got it out there, someone will say, 'hey that's Ray."'
While all of the reported assaults occurred in the Dallas area, Bowden warned that other victims may not yet have been identified and that women across the country should be on guard.
"These are the known ones," she told AFP.
"Unfortunately with sexual assault, it's so personal that a lot of people won't come forward, especially with this age group of women, there's still shame attached to it so they won't report it."