Graffiti has been found at the Lincoln Memorial, the Washington Monument, the World War II Memorial and the D.C. War Memorial, according to The National Park Service.
Two of the five acts of vandalism were found at the Lincoln Memorial.
U.S. Park Police spokesman Mike Litterst said Tuesday that messages written in permanent marker were discovered over the holiday weekend. Similar graffiti was found on a power box along the National Mall.
The Washington Monument references President John F. Kennedy's assassination and the Sept. 11, 2001 attacks, officials say. Litterst says because of similarities in what's written and the handwriting, it's thought the graffiti was left by one person.
The graffiti is being removed by the National Mall and Memorial Parks monument preservation crew, and they are using a mild, gel-type architectural paint stripper that is safe for use on historic stone.
The Lincoln Memorial, Washington Monument and World War II Memorial locations were successfully treated on Tuesday. The treatments will be applied at those locations as necessary and at the D.C. War Memorial on Wednesday and in the succeeding days, until all evidence of the graffiti is gone, according to the National Park Service.
They are asking that anyone with information about the vandalism call the United States Park Police at 202-610-7500.