ARREST MADE: At about 8:54 PM, on Wednesday, July 17, 2019, officers assigned to District D-4 (South End) responded to a call for a fight outside of the Boston Public Library located at 700 Boylston Street in Copley Square. On arrival, officers spoke with an adult male victim who stated that while working in the library’s computer section, the suspect, later identified as William Zaniboni, 49, of Boston, became irate without provocation and began yelling at him. When the victim asked the suspect to leave the building, the suspect indicated in a threatening manner that he would be waiting outside for the victim. As the victim was attempting to leave, the suspect approached him with a clenched fist and struck him once in the face. The victim then proceeded to defend himself by bringing the suspect to the ground. Once on the sidewalk, the suspect produced a spray can of an undetermined chemical agent, believed to be mace, and sprayed the victim in the face. The suspect then walked towards Exeter Street but returned to the scene a short time later where he was placed in custody without incident after being positively identified. Officers canvassed the area but were unable to recover the spray bottle used by the suspect during the altercation. The suspect will appear in Boston Municipal Court on charges of Assault and Battery by Means of a Dangerous Weapon and Assault and Battery.