The U.S. Park Police is searching for a person in connection to the graffiti that appeared on four national memorials and several other locations in February.

Messages espousing conspiracy theories were written on the Lincoln Memorial, World War II Memorial, Washington Monument, and the D.C. War Memorial as well as on a utility box near Roosevelt Island and on a stop sign near the Sylvan Theater over President’s Day weekend.

Scrawled in permanent marker, the markings included statements like “Jackie shot JFK” and “blood test is a lie… leukemia, cancer and HIV,” and made references to the September 11 attacks. Similar writings also appeared in Boston.

U.S. Park Police spokesperson Anna Rose described the man in the photos as a “person of interest in that investigation” but couldn’t disclose any additional information about why or how he was identified. USPP asks anyone with information to call 202-426-6710 or an anonymous tip line at 202-610-8737.

National Park Service workers were able to quickly remove the graffiti on most of the sites. It took a little longer to remove the markings on the exterior walls of the Lincoln Memorial because the marble is particularly porous, according to NPS spokesman Mike Litterst, but it has since successfully come off.

“Everything is back to normal as far as the condition of the memorials,” Litterst says.