The correct answer is: by removing the commentary that the professor is most likely involved in the gambling ring.
In order to be more objective, that means to keep away personal feelings or interpretation, the article must limit itself to the facts. The previous sentences did that; they described who was arrested and why, as well as the things that made the professor a suspect. In the sentence marked, the author doesn't have any evidence of the culpability of the professor, he only believes that.
Newspapers have a special segment were their opinions are written, they are called "Opinion pieces".
