Story highlights The Lincoln Memorial, Washington Monument and WWII Memorial were tagged

The graffiti included the phrase "Jackie shot JFK"

(CNN) US Park Police discovered several instances of bizarre, conspiratorial graffiti at the Lincoln Memorial, the Washington Monument and the World War II Memorial over Presidents Day weekend, officials said.

The graffiti consisted of text written in sharpie or magic marker, officials said, and included the words "Jackie shot JFK" and a message related to the September 11 attacks, according to US Park Police spokesperson Sgt. Anna Rose.

Graffiti near the Lincoln Memorial steps.

In all, graffiti was found at five locations: At a column and on the steps of the Lincoln Memorial, the side of the Washington Monument, the World War II Memorial and an electrical box.

The graffiti was discovered early Sunday morning, and it's believed to have been written late Saturday night. The instances all appeared to be related and officials believe they were committed by one person, Rose said.

Mike Litterst of the National Park Service said that officials were working to remove the graffiti, each of which was about the size of a football.

Read More