New York City police identified a suspect in the brutal subway mugging of a 55-year-old woman through the fraternity sweatshirt the attacker was wearing, caught on surveillance cameras.

Aidan Folan, 21, from Brooklyn, N.Y., is being held on robbery and assault charges in connection with the attack, Sgt. Jones of the New York police department public information office told ABCNews.com.

The March 9 attack left Dina Perez with a swollen and bruised face, bruises on her body, back pain and a broken wrist, according to ABC station WABC. Perez's attacker fled the scene with an envelope containing a small amount of cash.

Video released on Tuesday by police showed Perez walking down the stairs of the 18th Avenue subway station when a man suddenly attacked, beating the woman and rifling through her purse.

"Why, why you hit me?" Perez told WABC she said to her attacker. "He is strong. He keeps hitting me, hitting me, hitting me, hitting me."

Within 24 hours of releasing the video to the public, a tip led police to Folan. "It didn't take very long," Jones said. "Someone called Crime Stoppers and said this was him." The tip spurred an investigation that identified Folan as the suspect in the video.

Aidan Folan, 21, was arrested and charged with robbery and assault. (ABC News)

Perez later identified Folan in a police lineup, Jones confirmed.

Police said the man in the video was wearing a black sweatshirt with "Stugotz" and the number 27 on the back and Alpha Phi Delta, the name of a Greek college fraternity, on the front.

On what media reports say appears to be his Facebook profile, Folan can reportedly be seen in a photo wearing a similar sweatshirt. According to the profile, Folan attended St. Francis College, which has an Alpha Phi Delta chapter. The nickname listed on the Facebook page is "Stugotz."

Police declined to confirm or deny whether the Facebook page was that of the suspect.

Commenters responded to several media outlets' coverage of the attack online by identifying the accused suspect, Folan, through the attacker's sweatshirt seen in the video. One commenter on Gawker posted a link to Folan's Facebook and wrote "link to most likely suspect. take care of business guys."

Even with the arrest of a suspect, Perez told WABC she was still afraid. "It's crazy. I don't understand. Is he sick?"

Folan is due to be arraigned in Kings County court on Thursday.

Attempts made by ABC News to contact Folan were unsuccessful. It could not be determined if he has retained an attorney. Members of the Alpha Phi Delta St. Francis College chapter didn't immediately return a call seeking comment. St. Francis College didn't immediately respond to requests for comment.