One of the major differences in the cases, Darby said, is that the Fairmount Park Rapist, who is still at large, may have been lurking in the park waiting to pounce on unsuspecting women.
The attackers in this month's cases followed their victims into the park, police said.
It was about 7:30 Sunday morning when a 21-year-old woman set out jogging on York Street near 32nd, in Strawberry Mansion, and a man called out to her, Darby said. The woman turned, didn't recognize the man and continued jogging, he said.
As she made her way into the park, the man grabbed her and dragged her to a secluded wooded area on Edgely Drive near East Park Reservoir, police said.
The two struggled, and the man raped her and fled.
The woman, who was visiting from out of town, made her way back to a friend's house, where authorities were called.
Darby said that the victim has not been able to provide details for a composite sketch, but described her attacker as black with a medium-build, about 5 feet 6 and in his late 40s or early 50s.
She also said that he had close-cropped, salt-and-pepper hair, with a beard, and had been wearing a tattered blue shirt and light- blue jean shorts.
Police have beefed up patrols in the area, and investigators said that DNA taken from a rape kit and crime scene were being analyzed.
Darby encouraged people to use the park, but to go in groups. He also warned against using any handheld device that may cause distraction.
Tipsters can call police Special Victims Unit at 215-685- 3251.