An act of vandalism has led to the closure of the Lincoln Memorial until further notice. A splash of green paint was discovered at the base of the statue of President Lincoln shortly after 1:00 Friday morning. United States Park Police officials say the memorial is closed to visitors as they investigate the incident. Investigators will review video from surveillance cameras to help determine the perpetrator of the vandalism. Maintenance crews have been notified, however the clean-up work is not expected to begin until later this morning. Right now there is no estimate on how long the memorial will be closed to the public.