Thank you again for responses (no, have not been watching to many dramas 'fruit of the poisonus tree'-1st ever heard of). There is another side that concerns me greatly. As said in 1st post am worried, (the eldest, obviously) as I know what he went through for many years when abusing drugs, severe depression (which he still suffers as well as other health problems) attempted suicide on 4 occasions leading to stays in mental health hospital, and for the past good few years he has been 'in recovery'. I am worried that this may set him back and undo all the good work done since his journey on recovery started. I know he does have support from groups but do not know if I am able to do as much as I was hoping.

Many thanks to those who have replied (and yes, there is and always has been sibling rivalry between the 2 concerned) but I don't seem to be putting my point across very well and maybe I should have posted in general legal forum (only reliased that there was 1). I suppose the query I am asking relates to specific law of evidence and how it was/has been obtained. (from further digging) I know that if this information/intelligence (see 1st and 2nd posts) was/had been obtained this way by those conducting any (potential) investigation, then such evidence would be ruled inadmissable (any prosecuting authorities, police, hmce, dwp and others) as they are all bound by codes of practice. But my query still remains unanswered. It is the way that the information/intelligence/evidence had been primarily obtained (by threats and blackmail) by the younger sibling, and how this fact could affect any potential prosecution, for whichever way you look at it, the way these events have occured at the very least 'taint' the whole of the evidence. I suppose I was hoping for someone with legal knowledge to have come across this post and given a definitive answer. Is it possible for admin to copy this post and place in the general legal forum?

I agree with reply but it is the fact that (potential) prosecution evidence has been tainted/obtained unfairly/illegally, and because of this how would this affect a potential prosecution?

This is not exactly your everyday situation, however, I have tried to find answers on other websites but failed. I found this site and hope somebody can help. I am a distant relation of those involved and have tried to keep things simple but this has got to stop as been going on for a while. For information, the eldest, who has confided in me, is extremely ill, physically and mentally (this unnecessary stress is obviously making them worse). The youngest (who is causing the problems) is married with children and works full time. It surrounds the fact that the younger brother has been sending threatening texts to an elder sibling, and in telephone calls threatened to report the elder to DWP for, as he calls it ‘benefit fraud'. Indeed, the information the younger brother has obtained, has been done by way of threatening texts/phone calls which may even amount to blackmail or an offence of harassment, at least. My 1st query is if the younger brother goes ahead and reports sibling to DWP, how does the fact, the way he has obtained information/intelligence/evidence affect any potential prosecution? Could the way the younger brother has 'handled' the situation and obtained information, make this situation difficult for DWP to prosecute as the information/evidence was obtained unfairly (to the say the least), and as I think illegally, which could taint any evidence that the DWP seek to rely upon? If it is the case, that because of the way intelligence/evidence has been obtained by the potential DWP informant, and thus making any prosecution difficult, this would obviously put the eldest’s mind at rest, and will obtain further legal advice, if such a need arises.