The lewd behavior was captured on video. It shows him exposing and pleasuring himself in broad daylight in the doorway of a home on Corinthian Avenue.
Neighbors say it's happened multiple times to multiple people over the last few weeks.
A couple who spoke to Action News anonymously said the man exposed himself to them on June 3, and they reported it to police the same day.
"He was standing in his doorway, fully exposed, pleasuring himself to me, and like looking me in the eyes and smiling. All of this was really off-putting and really upset me," the woman said.
Philadelphia police confirmed another report on June 7.
"I just don't want it to keep happening to people, and I want the police to really move on this and put an end to the harassment that's been going on in our neighborhood for a while," said one of the victims.
Neighbors are alarmed because there's a school and community garden nearby, and many young children and families in the area. The Eastern State Penitentiary, which draws many tourists, is also in the neighborhood.
Rich Orth recently moved out of Fairmount to Delaware County.
"It's a bit more peaceful out there, we don't have really any incidents like this. I'm only back here for the day, and to hear that is happening in the neighborhood I used to live in, it's honestly not surprising, but it is disappointing," said Orth, who now resides in Glen Mills, Pa.
"I just hope he realizes what he's doing to people, it's not something that anybody wants to see," added Fairmount resident Nancy Yaros.
Police tell Action News the Special Victims Unit has been investigating the case as an indecent assault, and they've made "significant developments," but didn't share further details.
As the police investigation continues, neighbors are hoping for an arrest soon and are on high alert.
"Two days later, he was following really close to me on the street as well, like in my personal space. It's been emotionally draining and taxing to feel on edge," a resident said.