I think its extremely short sighted to allow teens to have a party with no adult presence.
More so in this case as his daughter and her peers were just 14-15.
I wouldnt do this and I wouldnt leave them with access to alcohol let alone drugs! [nb there would not be drugs in my house anyway!]
I wouldnt allow my 15 year old to be at a party that had no adult supervision.
The teens welfare would be my first issue, then of course the state of my house after too.
He is ultimately at fault for having drugs in his home
However the girl that sadly died chose to take them, but being 15 you can excuse her poor judgement.
He is old enough to know better.
A horrible tragedy all round, given that he has attempted suicide I think its fair to say that he is remorseful and probably will be for the rest of his life.
My sympathies are with the family of Isobel Jones-Reilly.
I know someone that died through recreational drug use similar to this case and its such a tragic waste.