An Interior Department spokesperson referred to the incident as "deranged vandalism." WASHINGTON, June 11 (Reuters) - The U.S. Department of the Interior said on Thursday it is investigating what appeared to be a large tracing of “8647” into the grounds of the National Mall in Washington, D.C. A Reuters photographer atop the Washington Monument saw the apparent marking in the grass near the World War Two Memorial shortly before authorities arrived at the scene. It shows the numbers eight, six