According to authorities, a man and woman were spotted on camera walking by the plaza on May 16 around 10:15 p.m.
The woman is seen wearing a multicolor scarf, red shirt, multicolor pants and black sneakers.
The man is seen wearing a blue shirt, gray pants and black sneakers, and appears to have a beard.
Using what police believe is yellow paint, the duo marks a section of the memorial with letters.
It's unclear what the graffiti said or stands for.
Officials with the plaza said, at this point, they don't believe it is an anti-Semitic message.
Those officials are also concerned by a video circulating of a group of males attempting to burn the flag of Israel nearby.
Recorded back on May 15, it shows a group of males attempting to take down and burn the Israeli flag along the Ben Franklin Parkway.
ALSO UNDER INVESTIGATION: DHS is also looking at this video of a group of males seen attempting to take down and burn the Israeli flag along along the Pkwy in Center City on May 15th.@6abc pic.twitter.com/gHgsEvQ4yR— George Solis (@GeorgeSolis) May 26, 2021
Through honks of horns, you can hear a person behind the camera laugh as one of the males slips down the flag pole.
The video also shows another male take a big fall as he leaps towards the flag.
The timing of the incident is troubling amidst the latest conflict between Israelis and Palestinians that unfolded overseas.
"Throughout the United States and in Europe, we are experiencing a dramatic rise of anti-Semitic incidents," said Philadelphia Holocaust Remembrance Foundation Executive Director Eszter Kutas.
Kutas said this flag incident occurred shortly after a pro-Palestine rally in the area.
"The conflict has fueled very strong sentiments on both sides and that's, of course, understandable but attacks on the American-Jewish community is anti-Semitism even if it's in response to a conflict that happening overseas," Kutas added.
Concerns are growing, even after the agreed cease-fire.
There did appear to be a police presence around the plaza on Wednesday.
Anyone with information is asked to call police.