According to authorities, a man and woman were spotted on camera walking by the plaza on May 16 around 10:15 p.m.
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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.
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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.
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.
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"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.