On July 12, 2012 around 7:45pm, Occupiers read a 9th Circuit Court of Appeals decision in MacKinney v Nielsen from 1995 and the California Civil Code 52.1. As the group finishes the first paragraph of the civil code, a random man walks up, grabs a hot-pink colored piece of chalk and draws a heart with the words “the police” next to it.
Within moments, the unknown man has 4 different LAPD officers detaining him with a 5th in his face. The man was not resisting yet there were about 40 other officers deployed to the scene haphazardly shutting down Spring Street just south of 5th Street.
Private security also assists the LAPD with this second police line formation.
This video shows Occupier reading California Civil Code 52.1, with people walking by on the sidewalk, when the unknown man writes on the sidewalk.
I believe this youtube video was taken towards the tail end of the second arrest:
This video has a small segment at the beginning that shows the second arrest and then shows clips from later in the night.