The "mad dad" is identified as ROBERT L. NORRIS.
http://www.indystar.com/article/20130106/NEWS/130106013/Father-charged-batter-after-taking-baby-from-library
Angry father faces battery charge after IMPD recovers missing child
8:15 PM, Jan 6, 2013
Written by Jill Disis
An Indianapolis man who briefly led police on a search in Downtown Indianapolis for a missing baby has been arrested and charged with battery on his infant daughter, police said.
Robert L. Norris, 18, was arrested Sunday, according to the Indianapolis Metropolitan Police Department.
Police say the mother, Rodricia Snow, 18, reported that her five-month-old child had been taken by Norris, after an argument at the Indianapolis-Marion County Public Library's Downtown branch.
Norris left the library with the baby, after he "pulled and twisted" the infant's arm "with a great amount of force," said a friend of Snow's, who was holding the baby in her arms, according to the IMPD report. The woman said she let go of the girl because she feared the infant's arm would be broken in the scuffle, the report said.
Snow told police that she feared for the child’s safety, and witnesses said Norris made statements alluding to possible child endangerment.
Norris left the library with the baby at around 12:10 p.m. and headed north on Meridian Street near St. Clair Street. A library patron followed him, but lost sight near 9th and Illinois streets.
Police and a fire department Search and Rescue Team searched the area and found both of them at about 2:30 p.m. in an alley within walking distance of the library. Both were unharmed.
Police say they will continue to investigate.