A federal agent tells Madison police it was a misunderstanding and he just went in the wrong restroom.  Twenty-seven-year-old Justin T. Fahy is accused of taking photos in a women’s restroom at a residence hall on the University of Wisconsin-Madison campus last week.  A woman says Fahy slipped his phone under her restroom stall and took pictures of her.  The Bureau of Alcohol, Tobacco, Firearms and Explosives has confirmed Fahy is a federal agent based in Madison.  Video surveillance shows he was in that restroom for at least 14 minutes last Friday.