The body was found in the 2500 block of North Mole Street at 6:30 a.m.
The sound of barking dogs apparently led a neighbor to the body. The victim was found halfway down a very narrow alley behind the houses there.
Investigators say she is a 26-year-old woman originally from Florence Township, New Jersey. Her name has not been released, pending family notification.
Police say the woman was found naked with marks around her neck that appear to be consistent with strangulation.
Police found her I.D. and some other personal belongings in a clear plastic bag.
That bag was found on the woman's face, police said. Inside they found a wristband from St. Joseph's Hospital.
Police don't know yet if she was murdered, or if she died from some other cause and was dumped in the alley. A ruling on her death may not happen until autopsy results come back, which may not happen until Saturday.
Investigators found a belt nearby and collected it as possible evidence. They also found a pair of women's shorts in the alleyway.
Residents of the neighborhood say they're hoping whoever did it gets caught quickly.
"I feel for the family, whoever it is. You take somebody's life, evidently you don't care, you're a danger to society," said Anthony Pridget.
"It could have been me. I could have been walking from the store or anything, going to my house," said Francine Young.
Police say they want to hear from anyone who may have heard or seen anything overnight.
Anyone with information is asked to call police at 215.686.TIPS (8477), text a tip to PPD TIP (773847) or through phillypolice.com.