contesting a policy

Hello, My aunt died in Jan of this year to cancer and in Feb we found out that a man had a policy on her. He called my uncle one day asking for the death certificate so he could collect. My uncle told him no and the man offered the family money and my uncle still refused asking the man where has he been through her sickness and that he will not profit from our familys loss. This man has found a way to provide a certificate and we are now trying to stop him from collecting, apparently my aunt did open a policy with her son as the original beneficiary (befor she was sick0 and in 2007 the policy was changed to this man as the beneficiary. She didn't find out she was sick until 2013. Its quite a mystery since my aunt isn't here to explain any of this . WE do kno that the insurance co called my uncle asking him if he knew several individuals, all of whom this man was holding policys on and his answer was no. In short we think this man is getting rich off huge policys and giving familys a smidgen of money compared to what hes collecting, we think hes running some legal scam.. What are our chances of winning ? We don't want the money, apparently this man had in fact been paying on the policy and renewed it when he learned of my aunts cancer, what do we do ?