MIL died nine months after giving financial POA to BIL and DH.
DH unwell and not local, BIL living with (and sponging off) MIL for several years. DH unaware BIL had started controlling money some time ago.
I'd agreed to sort out HMRC estate valuation and probate although they are both executors because, quite honestly, neither of them would know where to start.
DH obtained seven years worth of bank statements so I could check debts, loans etc. It's evident that BIL has been helping himself for years. There's around £40,000 worth of loans which he hasn't repaid and about £1000 a month in cash withdrawn. Before he moved in she was spending about £30 a week. She was housebound and extremely frugal.
Once POA was granted, he got even worse. He's taken the remaining £20,000 using her debit card or bank transfers and spent it on jewellery, sports equipment, gym membership, stuff for his girlfriend's pets and business and even gave his daughter £5000 when his mum, who had dementia, was in hospital.
I phoned the Office of the Public Guardian who said that it was outside their jurisdiction and was definitely a police matter.
I annotated over 100 pages of statements, marking up genuine expenditure and suspected theft/misuse of her money. The police have had it for two months but are totally unresponsive. They said they had enough evidence to interview him but were very busy. He's already pretty well known to them, having a criminal record for violence, theft, drug dealing over many years. As far as we know, the only time in prison was before his mother made him executor so he's not disqualified from being one.
I need to submit the estate valuation to HMRC but if I include the missing money it brings it over the IHT threshold. Obviously I have no guarantee that we'll get it back. HMRC have been unhelpful about how I should proceed.
I thought he was supposed to provide a statement of account once he started officially spending her money, but can't find anything online. Does anyone know what this involves?
MIL's solicitor was keen to take on the work but wanted money up front which we haven't got. Also, to instruct them to deal with probate he'd have to agree 
I have the information to submit the valuation, but obviously as an executor he needs to see it, at which point he'll turn nasty, possibly violent. DH is frail and can't cope with him.
Sorry, it's all a bit Jeremy Kyle, but if anyone can advise how to proceed and whether I've missed anything, I'd be very grateful.