Any legal eagles out there?

[abstibus]

I had a surprise phone call from my dead husband's sister-in-law yesterday . I haven't seen her for about 8 years. I will try to describe the scenario briefly and see if someone can tell me how to proceed. 4 brothers, A, B, C, D A died 25 years ago - no children B (my husband) died 11 years ago. Estate passed to me. C died 10 years ago (it was his widow who phoned me); one son. D died 4 years ago - wife predeceased him; no children. D sold his house and apparently deposited the money in an account he opened in my (dead) husband's name in order to be able to claim income support. I don't know how he managed to do this, as I thought money-laundering processes were so stringent that proof of identity, etc., was required. When s-in-law visits me this week, how should I handle it? I THINK she wants me to sign something to get the money released. I do not know if D made a will. The whole thing smells of fraud to me, and I do not want to get involved. Many thanks.