Plano, Texas (CNN) -- Texas police are hunting for a man they believe broke into the homes of four former members of the same sorority, then sexually assaulted them.
The alleged attacks took place over a span of months, and occurred in the Texas cities of Plano, Coppell and Corinth, according to police. No one has been named yet as a suspect, though Plano police last week released a video -- dated in April -- showing a man they believe is responsible for all four assaults.
The alleged victims -- all black females in their mid-50s to mid-60s -- offered similar descriptions of their assailant as a stout, black male in his late 30s to mid-40s. And all were alumnae of the same sorority: Delta Sigma Theta.
"He made it obvious to our victims that he knew information ... about them personally," said Plano police spokesman Andre Smith, adding that none of the women believe they knew their attacker in advance.
While ceding the sorority membership is a "common denominator" of all four cases, Smith cautioned against assuming that the accused attacker had only targeted this sorority's alumnae.
"We don't want to give a false sense of security to any other group that's out there," he said.
According to Corinth Police Capt. Greg Wilkerson, all the assaults occurred in "residential settings" between 9:15 p.m. and 4 a.m. when the victims were alone. The alleged attack in his city, 35 miles northwest of Dallas, took place on October 14.
The late-night setting, the fact the victims were often asleep and the alleged assailant's "attempts to conceal his identity" make it challenging to definitively identify the attacker, said Wilkerson. He noted that the Corinth police department is currently processing DNA evidence, as are other police departments.
Still, Wilkerson said that the suspect's physical traits -- weighing from 275 to 300 pounds and between 5-foot-7 and 5-foot-9 tall, in his department's estimation, and balding or with a close-shaven head -- were common, as were other characteristics like what he called the man's distinctive "swagger" as shown in the video.
Police described the video as coming from a surveillance camera, but they did not describe the specific source or location.
"There are some things ... that stick out -- his size, the glasses, the mannerism with which he walks," added Smith. "We know somebody knows (him) ... We just hope that they give us a call, so we can put a stop to this."
Wilkerson said that the nature of the assaults suggests the assailant was "possibly suspecting surveillance, spending some time around the areas ... prior to the attacks." The police captain added authorities do not know how the suspect learned details of the victims, speculating it may have been over the internet, by accessing an old directory or noticing would-be victims with Delta Sigma Theta jewelry, placards or other paraphernalia out in public.
"We want them to understand that their group is being targeted," Wilkerson said of the sorority's alumnae, urging them "not to advertise" their affiliation with Delta Sigma Theta and advising those who live alone to stay with a relative or friend until the case is resolved. "(But) we don't want to create any pandemonium."
The sorority's Washington-based headquarters, in a statement Monday, urged all its members in the Dallas area to take precautions.
"To think that our members are being targeted is disturbing and extremely disheartening," said Cynthia M.A. Butler-McIntyre, Delta Sigma Theta's president. "Until the individual responsible for these crimes is brought to justice, we will continue to remain in close communication with one another and law enforcement officials."