Suspect Elias Rodriguez, 31, allegedly shouted “Free, free Palestine” after the Wednesday night's deadly shooting at the Capital Jewish Museum in Washington D.C.

WASHINGTON — In her first time talking to the press as the U.S. Attorney for D.C., Jeanine Pirro gave updates about the federal investigation into the man charged with shooting and killing a soon-to-be-engaged couple outside the Capital Jewish Museum Wednesday night.

A solemn vigil was held outside the White House to remember Sarah Milgrim and Yaron Lischinsky, the young couple who worked together at the Israeli embassy in Washington and were fatally shot after an event at the Capital Jewish Museum.

Identifying who will go from anger to violence is like "trying to find which piece of hay is going to become a needle," one expert said.

FBI agents left a property in Chicago's Albany Park neighborhood that is connected to the suspect in a deadly shooting outside the Capital Jewish Museum in Washington D.C. with boxes of evidence in hand Thursday afternoon.