Tulsidas Balaram, who passed into the ages last week, was a member of the Indian football team which reached the semis at the Olympics and won an Asian Games gold medal.
Nine witnesses have been attacked so far and three of them have died.
Sunanda's mail and messages on social media should be taken as a "dying declaration", the police told the court, which reserved for June 5 its order on whether to summon Tharoor as an accused in the case.
The police has named Tharoor as the only accused while also alleging that he had subjected his wife to cruelty.