Police have offered a $5,000 reward for information leading to the arrest of the rapist.
They believe the same man may be responsible for two brutal attacks on Friday and two others back on October 22nd.
"In each one of the incidents women are coming out of their apartment into the hallway, a man with a ski mask forces them back into their apartment and either ties them up or, in this last case, duct tapes them for hours and sexually assaults them," said Lt. Thomas McDevill.
Investigators say the man in the sketch tortured two roommates on the 4400 block of Spruce Street on Friday.
They believe the same man may have attacked a man and a woman on October 22nd on the 900 block of Clinton Street.
Police are also linking the man to an attempted attack on October 21st on the 1200 block of Lombard Street. Neighbors of the woman involved in that incident chased the suspect off.
Police released a sketch of the suspect and say he weighs 190 to 200 pounds, is around six feet tall and has a dark, unshaven complextion and a goatee.
Since getting word of the attacks, women in the area are looking over their shoulders.
"Today I was walking on the main streets as opposed to side streets because I was afraid," said Dena Pichett.
"Definitely undergrads who are walking around drunk at 2:00 a.m. need to seriously think about what they're doing because this is really serious," said Sarah Chobot.
Police believe the suspect lives in the area of 50th and Baltimore. Investigators say he has used the victim's ATM cards a couple of times at that location.