Until about 6pm Thursday night, three white crosses graced the Boston Marathon bombing memorial site at Copley Square. But many thought there should also be a cross at the site to honor fallen MIT police officer Sean Collier.

Kevin Brown, a Brockton man who has spent much of the time since the bombings at the memorial display, decided to remedy the situation. He went home and built a special cross and placed it beside the other three.

I spoke to Mr. Brown just as he finished putting the fourth cross in place.

Click play to see the interview with the man who made the cross for Sean Collier.