"There is a widespread belief that he has been tricked or framed by some vested interests however it's difficult to substantiate the same without proper investigation," Fadnavis wrote in a letter addressed to Sports Minister Vijay Goel.
India's build-up to the Rio Olympic Games was rocked when medal hopeful Narsingh was found to have tested positive for a banned substance.
Narsingh, who was picked ahead of the double Olympic medallist Sushil Kumar to represent India at the Rio Games, has been put under provisional suspension.
"Looking at his past record and the way he was preparing for Rio Olympics, it seems impossible that this may happen. He has been taking utmost care in his diet and was under proper training in accordance with the international norms."
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Fadnavis further said, "Hence I request you to kindly look personally into this case and to go into the depth of the incidence. The test may be conducted again and through scientific process, we should try to ascertain whether something has been done only with a view to make him fail the test.
"I sincerely hope that you would take the steps with urgency and give justice to the medal aspirant sportsman our country."
Fadnavis yesterday told the state Assembly that "justice" for should be done to players like Narsingh.