Christian Morales, a 20-year-old Harlem man was arrested Friday, and charged with second degree aggravated harassment and committing a hate crime for assaulting a Sikh Columbia University professor last fall.

Morales is accused of pulling the beard of Dr. Prabhjot Singh, an assistant professor at Columbia's School of International and Public Affairs, Sept. 21, 2013.

Singh was approached by a group of young men on bicycles while he was walking home in upper Manhattan. The suspect was reportedly part of a group that allegedly called Dr. Prabhjot Singh "Osama" and a "terrorist;" punched him in the face and head, kicked him and pulled his long beard.

According to the police, the men "made anti-Muslim statements and then they began punching the victim in the face," Columbia Spectator reports.

The professor suffered severe bruising, swelling, small puncture in the elbow, injuries to his face and a fractured lower jaw following the brutal assault near Lenox Avenue, NY Daily News reports.

According to the New York Police Department, Morales admitted that he present at the time of the  incident and pulled the complainant's beard, am New York reports. Police officials said that in 2010, Morales faced arrest for carrying a loaded gun in South Bronx.

Singh wears a turban and has a beard in accordance with his Sikh faith. The 31-year-old professor also practices medicine in East Harlem.

The followers of the Sikh religion have been frequently targeted in the United States, most of the time mistaken for Muslims. The 2012 August shooting at a Sikh temple in suburban Milwaukee left six people and the white gunman dead.

Singh has always been vocal about hostility against Sikhs. In a 2012 op-ed titled 'How Hate Gets Counted' in The New York Times, the professor accused the federal government of not taking appropriate action against anti-Sikh violence.

The article claimed that it was wrong "to assume that every attack against a Sikh is really meant for a Muslim. We must do away with a flawed and incomplete assumption of 'mistaken identity' regarding Sikhs; until we do, we will all be the ones who are mistaken," Singh said in the article.

At the time of the September incident, Singh said that he would invite his attackers to his place of worship and educate them about Sikhism.

A video grab of the incident.