Investigators made the discovery in the 900 block of Tustin Road in the city's Fox Chase neighborhood on Thursday afternoon.
The person of interest police are searching for is the victim's boyfriend.
"We searched for her for six days," said Martha Lee Fred of the search for her sister, 29-year-old Melody Rivera, who the family last heard from Halloween night.
When police found a woman's body Thursday afternoon, Fred got the news she and her family had been dreading.
"It turned out, unfortunately, that it indeed was her," she said.
"They found a shallow grave and the body," said Philadelphia Police Deputy Commissioner Frank Vanore of the discovery.
The medical examiner has not yet determined a cause of death, but police are looking for Rivera's boyfriend, Geovanni Otero, who is 29 years old.
He is considered a "person of interest." Police say he's already wanted in another case.
"He's wanted for violation of parole. I believe he has felony arrest that put him on parole, so he could be considered dangerous," said Vanore.
Police say Otero had a dispute with the victim before she went missing. That began the initial police investigation and search.
"There was some type of dispute between them, and during that dispute, Otero was there so that's why we want to talk to him," said Vanore.
Rivera's family is asking the community to help police find him.
"(We are) begging and pleading with the community. Just come forward if you know where he's at. If you have any information, just help us," said Fred.
Rivera's mother, Maritza Garcia, was heartbroken as she hugged Rivera's 11-year-old daughter in front of the family's home.
"My granddaughter's suffering," said Garcia through tears. "It's like I've never felt his heartbroken in my life. Took my baby from me.
The heartbroken family is now hoping for justice.
"She was taken far too soon and it's unfair," said Garcia.
The Philadelphia Police Department asks anyone with information on the whereabouts of Geovanni Otero to contact Homicide Detectives at 215-686-3334 or to submit a tip via their anonymous tipline at 215-686-TIPS.