District police on Friday arrested a man in connection with the beating of a 39-year-old part-time George Washington University professor who was found critically injured on a sidewalk near Dupont Circle, according to authorities.

Police said the altercation began as the suspect and co-workers were transferring newspapers from one delivery truck to another about 4:15 a.m. Sunday at S Street and Connecticut Avenue NW.

Police said in an arrest affidavit obtained by The Washington Post that the suspect, identified as James Brown, 38, of Southeast Washington, punched the professor after feeling threatened, checked his pulse and “got back into his truck and began delivering his newspapers, leaving the victim on the sidewalk.”

The professor teaches at George Washington University in the department of exercise science. Lynn Goldman, dean of the School of Public Health and Health Services, issued a statement Friday extending well wishes to the professor. His condition could not be ascertained, but police said in the affidavit drawn up Friday that the professor suffered a collapsed lung and severe head trauma and was in a medically induced coma.

Brown was being held by D.C. police pending a possible appearance in D.C. Superior Court on Saturday. He is charged with one count of aggravated assault.

The Washington Post confirmed that Brown is a “casual laborer” whose job was to jump off trucks and put papers into single-sale boxes around the city. He is not an employee of The Post but was hired by agents who are contracted by the newspaper.

The arrest affidavit says that the professor and deliverymen were in a discussion when the professor was punched in the face, fell and hit his head on the street. A witness told police that the professor’s “hands were down at his sides” and that he was “just standing there . . . in a non-threatening matter.” Another witness told police that the suspect repeatedly kicked the man in the head as he lay on the ground.

But one of the truck drivers told police that the professor appeared intoxicated and twice placed his hands on his chest. He then said he saw the man walk up to Brown and he “heard a loud thump.”

Brown told police that he punched the professor after he walked toward him “with his arms raised and reaching for something, yelling and screaming,” according to the affidavit. Brown also told police that the man shoved him. After punching the professor, Brown and another man dragged him off the street and onto the sidewalk.