ROME — A homeless man was detained on Tuesday in connection with the death of a 19-year-old student from Wisconsin who disappeared just hours after he landed in Rome, the Italian authorities said.

The man, Massimo Galioto, 40, of Rome is suspected of involvement in what the police in Rome said was the murder of Beau Solomon, a visiting student from the University of Wisconsin-Madison, who was found in the Tiber River on Monday with a head wound and blood on his shirt.

Mr. Solomon disappeared after going to a pub Thursday night, not long after he arrived in the city for a summer program at John Cabot University, an American school in central Rome.

The university said in a statement that Mr. Solomon’s roommate, who has not been identified, was with him at a pub in Trastevere, an area near the university known for its night life, and that he lost contact with him around 1 a.m.