>> the train stops at the 42nd street station, and transit police arrive shortly after. >> he didn't get two steps off that train, and he was in handcuffs. >> the perpetrator is identified as mario valdivia. >> my heart was still beating, just pounding, thinking, gosh, i've got to make sure they take him down. >> he's arrested for forcible touching, a misdemeanor offense, and he's found to be an undocumented immigrant. released on bail, he commits a similar offense on the subway just six weeks later. >> he was what i would call a menace to society. >> valdivia pleads guilty to both crimes and serves four months in jail. registered as a sex offender, he awaits deportation. nicola has no regrets, and continues to encourage women to defend themselves. >> don't let anyone take your power away and don't let good manners ruin your day, either.