Over President’s Day weekend, a crowd gathered at the National Mall in D.C., and around 11 p.m. one of those people was defacing national monuments. Park police discovered strange graffiti first at the Lincoln Memorial, where there were two messages found, and later at the Washington Monument, the World War II Memorial, the D.C. War Memorial, and on a nearby power box.

Because the handwriting and the messages are similar, park police believe one person was responsible for all the messages.

Their content was mystifying. The messages referenced the JFK assassination and the 9/11 attacks. “Jackie shot JFK,” read one message. Another message read “blood test is a lie… leukemia, cancer and HIV.”

These message were written in tight, small spaces, about the span of a person’s hand. The National Park Service is cleaning them with a mild paint-stripper that’s fine to use on old stone; there’s no news yet as to who did this but police are searching for the culprit.