I told the police they were not allowed back to the property?

On what authority did you inform the Police he couldn't return to the Property? This is not within your remit, only the Tenant or a Judge can end a Tenancy.
I can't believe the Police went along with this!
You need urgent Legal advice as it appears you have carried out an Illegal eviction.

Hi Steven
I don't think it's a police matter to determine if somebody can or cannot occupy a house. I am surprised by the bail conditions, if this is indeed his family home.

As landlord you cannot unilaterally draw the tenancy to an end without a Court order (ultimately) so by barring him from access you are in the wrong. I have been involved with cases of landlords taking possession of property having assumed abandonment, only to be challenged (and losing) in Court. On that basis I do think you are in the wrong. If he has a tenancy you cannot bar him from access, whatever you think of his behaviour. The bail conditions are a matter for him and the police.

I do write as a tenancy adviser and, as ever with such situations, there may be more to it than meets the eye and you would need advice from somebody familiar with the bail process (luckily I am not) and criminal law.

There is an awful lot seemingly missing here: it doesn't make sense. I mean firstly how was the poster made aware that the husband had gone "berserk"? Is this a separate house or is everyone under the same roof?
Secondly, why would he have gone off the rails over the poster's daughter's death since they weren't even related, he being the poster's partner's husband.
Thirdly, the poster said that "we" let the property to them. Does that mean the poster and his partner jointly own the property? I am very confused.
And a 10-year tenancy? So no AST presumably?
And as suggested in another response, this may well be an illegal eviction since there must be at least 3 months' notice period for any notice given on or after 26 March 2020. This is because of coronavirus.
The poster should go back to the lawyer who issued the s21 notice for advice.

You should obtain professional legal advice immediately

Reply to the comment left by SimonP SimonP at 10/07/2020 - 11:23
SimonSimonP is correct.
Steven's position seems dreadfully muddled. Remove the muddle and the irrelevant bits. Who drew up the presumably 10 years Lease, was it stamped etc.? Surely not a 10 years AST, I was never a conveyancer, does that creature exist?
Respectfully suggest he ought to go to a different lawyer with solid experience of professional negligence. I write as a former PI Insurance defence solicitor. Not wishing to seem overbearing, Steven must take ALL his papers with him along with diary notes etc., a good memory and his partner! Be advised, a good PI Insurance Solicitor will not be cheap but do you want your property back or its value if you have been stitched up by provable negligence or are you prepared to just grin and bear it? Do your sums!
It is about 50 years since I handled any criminal work but my memory suggests the bail giver may specify where the bail receiver may or may not stay or go to.

Not a lawyer, but it seems the only saving grace in this is if the police imposed bail conditions preventing the tenant from returning to the property (which may be because he was considered a risk to the property). Otherwise, as others have said, you can't unilaterally evict someone and the arresting police should not have complied with your request to take the keys off the tenant. The police may have been a bit naive in going along with your request.

I have had to re-read this to understand the family here. I think Steven means daughter's husband, in which case the rest makes sense. I am sorry for your grandchildren, they seem to be the ones who are suffering.

Reply to the comment left by Puzzler at 10/07/2020 - 13:09
You may well be right Puzzler but I gave up long ago trying to second guess what people really meant when they post messages.
If they cannot correctly articulate all the facts, then they'll not get advice appropriate to their enquiry: in which case everyone has wasted their time, including the poster.
Not saying that that is what has happened here, I am just generalising.

Reply to the comment left by Lindsay Keith at 10/07/2020 - 12:09
There is no maximum length of an AST. BUT - if more than three years should be done by deed (needs to be written by a solicitor) and if more than seven years must be registered at the Land Registry.

If not executed properly, it will merely be an agreement for a tenancy (the validity of which would need to be interpreted by the Courts).

The name is a misnomer.

Reply to the comment left by SimonP SimonP at 10/07/2020 - 11:23
An AST can be for 10 years - see my comments in reply to Lindsay Keith.