Money extortion attempt after mental harassment

My brother Ravi has lent 60 lakhs to his close friend Kiran without any agreement.Kiran had returned some amount and had promised to return some of the remaining amount in January and the rest by June. When Ravi asked for money in Jan,2021 Kiran asked for one month time.So Ravi went to Kiran's home on 5th Feb but Kiran said he's unable to find his chequebook and his internet banking facility is not working.he asked to come the next day.Next day also he made similar kind of excuses.When Ravi went to Kiran's home on 8th,Kiran was sick.So Ravi took him to hospital.Kiran was found dead under suspicious conditions in his home the next day. Now Kiran's wife is claiming that Ravi pressurized Kiran for money and so he died and is threatening Ravi to get him arrested. Postmortem reports are yet to come.Now we got to know that Kiran had borrowed lakes of amount from few more people without agreement. 1)Can Kiran's wife get Ravi arrested for Kiran's death? 2)Can she claim that the money which Kiran returned to Ravi was actually borrowed by Ravi from Kiran and Ravi has to pay him back? I think Kiran's wife has all the money Kiran borrowed from people with her and she can spend it to get the case in her favor. Please suggest some ways to defend Ravi in both cases.