Ominous graffiti reading "We will bring this plane down" in Arabic was written on the underside of the EgyptAir jet that crashed en route from Paris to Cairo on Thursday morning, The New York Times reported on Saturday.

The note — which, at this point, is nothing more than a coincidence — is believed to have been written about two years ago by aviation workers at Cairo Airport who were sympathetic to the Muslim Brotherhood, according to three Egyptian officials.

The workers also wrote "traitor" and "murderer" in reference to Egypt’s president, the Times reported, "playing on the phonetic similarity between the last two letters in the plane’s registration, SU-GCC, and the surname of Egypt’s president, Abdel Fattah el-Sisi."

The officials did not specify who found the graffiti, which was evidently documented by the airline after it was discovered in 2014.

Three in-flight security officers, Walid Ouda, Mohammed Farag, and Mahmoud el Sayed, were on flight MS804 when it crashed, according to The Times, but they had no criminal history or record of suspicious behavior.

Officials said it is protocol to have two security personnel on every EgyptAir flight. Previous statements from aviation authorities indicate that the third guard onboard flight MS804 was a trainee.

Flights over Egypt have encountered trouble on several occasions in the past year, prompting aviation authorities to instruct pilots to fly above 26,000 feet in the region.

In October 2015, a Russian airliner crashed in northern Egypt, killing all 224 people on board, and an EgyptAir flight was hijacked and forced to land in Cyprus in March, prompting an hours long standoff. No one was harmed in that incident.

In 2002, an EgyptAir Boeing 737 went down near Tunis-Carthage International Airport, killing 14.

In 1999, an EgyptAir flight from Los Angeles to Cairo, with a stop in New York, crashed into the Atlantic Ocean, 60 miles off Nantucket Island, killing the 217 people on board.

Greece's civil-aviation department said that while it was in contact with the pilot, 36-year-old Capt. Mohamed Shoukair, he seemed "in good spirits and thanked the controller in Greek," after he was cleared to exit Greek airspace. Shoukair had logged more than 6,000 flying hours, and his copilot, 24-year-old Mohamed Mamdouh Assem, had logged just over 2,000 flying hours.

Greek investigators said they found body parts, debris, and personal belongings of passengers in the Mediterranean on Friday, 140 miles north of Alexandria on Egypt's coast. French investigators confirmed on Saturday that smoke was detected in "multiple places" on board the doomed jetliner in the minutes before it crashed, likely indicating "the start of a fire."

Reports have also emerged that search crews have found the black boxes from the plane, though that has yet to be confirmed.