He, as well as most Western nations, have blamed the Russian security forces with the help of the Ballon Cat investigative website, who had identified some of the team which had been trailing Navalny.

He called them up.

He pretended to be a senior security official investigating the poisoning operation, and he got a full confession.

His an excerpt from the phone call.

Okay, then tell me what kind of clothes it was applied on.

What was the main focus?

What's the riskiest piece of clothing in theory?

Well, underpants, underpants.

We spoke to the man who sat next to Alexei Navalny during this phone conversation.

Crystal grows if the lead investigator off balance.

Yet it was definitely the most incredible thing anybody can, um can can live through.

What added to the surrealism of the moment is that we hadn't I hadn't slept the whole night working on the final touches to the investigative reports that we would publish later that day.

Eso at 4 30 in the morning, there was this phone call and I think can Giovanni also had not stopped that night much so it was all kind of in a slow motion.

And when it happened, I really thought I was dreaming.

And this could not be happening in your time.

Crystal, Who did you decide to call?

Well, actually, the original plan had bean toe Onley confront the actual suspected poisoners for Navalny to call them up and to say Hello.

I'm Navalny.

Why do you try to kill me?

And to try to get their reaction?

This, we thought, was going to be a funny moment before we published the investigation.

But a midway through the Cole sequence, Navalny says, Well, I'm not getting any reaction.

They were hanging up.

So how about I just do a prank and call one of them but Impersonating a top security officer?

So we had about two minute prep session to think of what name might work and who might be the office that they call from.

He decided on calling on behalf of a non existent eight tow.

The chief of the Security Council of Russian Equal Partnership was probably one of the most senior security officials, probably the most senior security official in Russia and he was going to call and ask for a quick report on what went wrong in Tomsk, the place where the volume was poisoned.

I was completely, uh, determined that this would yield in a in a hang up and somebody just putting the phone down.

It went through the first five minutes and I thought, Okay, there is a chance.

Actually, this guy might confess, and within about seven or eight minutes, he had made the first confession.

Navalny stayed in character for for 49 minutes and kept bullying the poor guy to give them more information and more information.

And at the end, I really thought I had gone through a dream.

It's probably as unique as the experience he had a living through, another truck poisoning on.

I think once he does that he is ready for anything.

But I could see in his face that he was withholding the emotion and the emotion must have been extremely powerful appearing.

Somebody explain to you why medics coming to save your life is a terrible thing to happen.

I think it took him, ah, lot of adrenaline to go through it.

And at the end he just essentially collapsed.

He went back toe to his home to have a rest because he had nothing to say.

And he couldn't say nothing until we met later in the day and we all wondered whether that had really happened.

Or was it a dream?

Was it a dream?

Well, let's get the thoughts now of our Moscow correspondent, Steve Rosenberg.

Such fascinating details in that phone call Steve 49 minutes long.

What was your reaction when you listen to it?

Well, I mean, Lucy, what an incredible story.

You'd be hard pressed to come up with a more bizarre telephone conversation.

Telephone call, would you?

I mean, Alex in the valley picks up the phone and telephones one of the security officials security agents alleged to have been part of this clandestine FSB hit squad in order to to shallow him and then to poison him.

It was incredible.

49 minutes on this man, Constantine Kudryavtsev, clearly completely duped.

Completely taken in believing that Mr Divinely Waas who he said he waas this Russian security official.

Andi, uh, Mr nobody able to extract some fascinating details of the operation to kill him, including the the detail that the novel Chalk Poison, this chemical weapon seems to be implanted in a pair of his underpants.

Also interesting.

Mr Kudryavtsev made it clear that the dose of novel chalk would have bean enough to kill Mr Nonviolently if the plane on which Mr the violin had been flying to Moscow hadn't made an emergency landing so quickly and if the paramedics on the ground hadn't acted, acted so quickly.

Fascinating stuff.

Yeah, we heard Steve how difficult it was for Alexey Navalny to sit there and hear that kind of detail that it was only the urgent medical care he received that saved his life.

It was really amazing to get some of that information, but I'm wondering what the reaction has Bean not just from the Kremlin but from others in Russia to this interview.

The reaction has bean, as expected, whenever the Russian authorities are accused of something, whether it's poisonings or whether it's meddling in U.

S.

Elections or sending Russian troops into eastern Ukraine, the reactions always denial.

We heard a denial yesterday from the FSB, the Russian Internal Security Service, which called the recording a fake.

It said it was a provocation organized by foreign intelligence services.

Today, the Kremlin has commented and said, Well, the FSB has said everything.

We have nothing more to add.

But they did add.

President Putin's press secretary said that Mr Divinely suffered from delusions of grandeur and a persecution complex.

Nothing surprising, really.

In the Kremlin's reaction to this social media, though, Steve Well, it's been all underpants, really.

Lots of humorous posts about underpants plays on words, many post suggesting that the FSB cleans Mr the Violence underpants.

Because this man, Mr Kudryavtsev, it seems his role in the Operation Waas to clean up the evidence and to organize the cleaning off Mr Levine is close to get rid of the evidence.

It's fascinating stuff is that it's remarkable on many levels.

You know, the fact that the victim calls one of the assassins alleged assassins the fact that the investigative team, the investigative journalists and the citizen investigators were able to identify the members of this clandestine FSB hit hit squad using databases older, new using passenger logs using mobile phone records.

And they were able to put this jigsaw together on come up with names and numbers on that Steve, they may deny it.

But surely this is hugely embarrassing for the Kremlin end for the FSB.

Oh, absolutely.

It's embarrassing for Mr Kudryavtsev, who was taken in.

It's embarrassing for the FSB.

It's embarrassing for the Kremlin.

Only last week, Vladimir Putin and his big end of year news conference was saying, Well, yes, we we may have Bean following Mr Levine early, but poison him know if we have wanted to kill him, then we would have made sure we did the job properly.

I mean, the Kremlin has continually denied that the Russian state had anything at all to do with the poisoning off the Kremlin's most vocal critic, Steve.

Thanks for joining us from Moscow.