Mine was years ago, with the IC SN checks. Bear in mind that I have very little history of mental illness or self harm. But, I was reasonably honest with them. I told them I had purchased SN in case I came down with a debilitating illness in the future. So- they knew it was for suicide but, not imminently. It wasn't a total lie. I would use it under those circumstances and, I had already had it for 6 months when they showed up. So- I'm hardly impulsive!
But, it was a bunch of fencing really. I wanted to be honest with them. I don't see why I should lie. Suicide isn't illegal and I believe I'm mentally competent. But yeah, it was a whole bunch of give and take. They asked to see the product. I told them I'd allow that so long as they handed it back- which we both did.
They weren't at all comfortable leaving me with it but I was firm but polite. They felt better when I agreed to be put in touch with a helpline. Who, as it turns out were much more manipulative and unpleasant than the police!
One officer seemed to genuinely care but, it was obvious that it was a box ticking exercise too. I suppose they have to feel confident enough that we're 'safe'. At least in the immediate future.
Personally, I don't tend to think that being obstructive towards them is useful. Not in an aggressive way anyway. Surely, that just makes it look like we have more to hide. But then, part of the way through, even I was starting to wish I'd just lied about it and said I'd gotten rid of it.
I think it does depend on a person's history too. Obviously, if there are previous attempts or sections on file, they are likely to be more nervous I imagine.