As the waiter scurries away with our orders, I lower my voice and remark to the man sitting opposite me: ‘You know I’ve got to ask this – did you abduct and kill Madeleine McCann?’

It is just after 7.30pm on Friday in a restaurant in the port city of Kiel on Germany’s Baltic coast, and I’m having dinner with Christian Brueckner, convicted child sex offender, rapist and violent thief – and the prime suspect in three-year-old Madeleine’s disappearance in 2007.

To widespread concern – indeed disbelief in some quarters – Brueckner, 48, was released from prison last month after serving six years for the rape of a 72-year-old American tourist.

Tonight he is wearing a crumpled white shirt and shabby jacket, and moaning to me about his lot: the endless police hounding, his pariah status, being bounced from town to town, hostel to hostel.

But the prospect of pork schnitzel with fried onions, mushrooms and french fries temporarily lightens his mood. As he relaxes, I decide to strike.

Brueckner has never publicly addressed the question, not to a journalist or even the police. It is registered with a glancing smile and a deep sigh.

Then he sips on his half-litre glass of pilsner, leans forward and, his voice rising above murmured conversations and ambient background music, says with wide-eyed theatricality: ‘No, of course not.’

He gives the impression that he thinks the notion simply absurd. I remind myself of his horrifying record.

Brueckner has a string of convictions for theft, aggravated theft, sexual abuse and attempted sexual abuse of children, performing sexual acts in front of minors and possession of child pornography.

Christian Brueckner (pictured in court last year) is a prime suspect in the disappearance of Madeleine McCann

Meeting with the convicted child sex offender, rapist and violent thief, ROB HYDE asked him: ‘Did you abduct and kill Madeleine McCann?’

He raped the American tourist in Praia da Luz – the same Portuguese resort where Madeleine went missing two years later. And during the attack, which he filmed, he whipped the woman. She has since died.

He was also alleged to have tied up a teenage girl and forced sexual acts on her while filming; carried out a masked attack on an older woman; and raped Hazel Behan, an Irish woman who has waived her right to anonymity, in 2004 when she was 20. Not for nothing is he known as one of the world’s most reviled criminals.

‘Write this down, write this down,’ he urges, jabbing with his index finger.

‘Of course, there are many more things I can say here about all of this, but my lawyers and I have discussed this, and so I need to adhere to what we have agreed,’ he says.

‘And this means not going into any further detail at this time on this.’

Investigators believe Brueckner lived and worked in the Algarve in the years around Madeleine’s disappearance – waiting tables, selling advertising for English-language papers, tending gardens – while also committing theft and dealing in drugs.

A phone number that investigators say is linked to Brueckner registered a ping near the Ocean Club, where Madeleine and her family stayed, on May 3, 2007, the night she vanished.

‘Where were you that night?’ I ask him. ‘Who were you talking to? Do you have an alibi?’

Brueckner stares at me with piercing blue eyes, but says nothing more on the subject of Madeleine McCann.

But over the course of the evening he will say plenty more on his perceived persecution – his mood veering dangerously between jovial and eerily controlling.

We’d met less than an hour earlier. Two minutes before my cab pulled up at the Dietrichsdorfer Hof Hotel, his home of three days, he texted me saying: ‘They’re throwing me out!’ I found him embroiled in a stand-off with staff. Other guests had complained and the manager told him to pack his bags and leave.

‘I don’t think anyone has actually complained about me – I don’t think anyone even recognised me,’ he says. ‘It’s because of the deliberate over-the-top police presence in the hotel. They stand outside my room and follow me down to breakfast.’

One night was spent on a football field after being turned away by a homeless shelter.

He claims the police even followed him there – illuminating his sleeping bag with their car headlights to keep him awake. But perhaps they had cause.

A year ago, a court in Braunschweig, northern Germany, acquitted him of three separate cases of rape and two of exposing himself to children.

‘Brueckner stares at me with piercing blue eyes, but says nothing more on the subject of Madeleine McCann,’ writes ROB HYDE

Madeleine went missing in 2007 in Praia da Luz – an area of Portugal investigators believe Brueckner lived and worked in around that time

Try as he might, [Brueckner] says that he cannot shake off the link to Madeleine McCann

This was despite a warning from a forensic psychiatrist that Brueckner had ‘psychopathic’ tendencies and that it was ‘highly probable’ he would commit sex offences again if allowed to roam free.

Little surprise, then, that he strikes fear wherever he goes.

Philipp Marquardt, one of his lawyers, says he must wear an ankle tag and carry a mobile phone, both of which are monitored round the clock. ‘It infringes directly on his human rights,’ Mr Marquardt says. ‘Frankly, I believe the police are doing all this because they are trying to encourage a stigmatising of Mr Brueckner, to the extent he will feel so desperate that he takes his own life. It is like they want him to feel all doors are closed and there is no way out for him.’

Mr Marquardt has suggested to prosecutors in Braunschweig that Brueckner is allowed to leave Germany for six months until the furore settles. Then he could return and live anonymously.

Neither this nor his complaints have found receptive ears, however. Nobody, it seems, wants a monster in their midst.

In the small town of Neumunster, locals claimed to have spotted him wearing a fake beard and begging for free pizza from Domino’s. Councillors urged everyone to be on their guard, especially girls and women, and called on people to print images of Brueckner’s face and give them to pensioners without access to the internet.

As tensions grew, there were calls for violence and speculation about where he was living.

Eventually Brueckner was spirited from the town by police and he later found his way to Braunschweig where he demanded an audience with chief prosecutor Hans-Christian Wolters, who has said he is the only suspect in the case, and that he has ‘strong evidence’ that he is responsible for Madeleine’s abduction and death.

From Braunschweig he moved from town to town before arriving in Kiel.

I found his company exhausting. He flips at high speed from jokes and high spirits to gloomy ranting about the police and German investigators.

They just want to frame him, he says, and he even believes they will try to kill him.

‘I don’t expect to live long. They are doing everything they can to silence me. I have been completely set up.

‘The investigators have just created a phantom bad guy, and to this phantom they have added the name Christian Brueckner. But I am not this man.’ Try as he might, he says that he cannot shake off the link to Madeleine McCann.

A year before she disappeared, an associate claimed to have found videos at Brueckner’s house showing sexual violence. But the witness has a criminal record which complicates his credibility.

He hates being interrupted. I try to butt into one of his interminable rants, but he barks: ‘Listen, don’t say anything’

Madeleine-related television appeals in 2013, 2020 and 2021 on a Crimewatch-style German TV show generated hundreds of responses.

But Wolters concedes there is nothing yet to take to court. He has told journalists that he holds a piece of ‘strong’ evidence that he has not disclosed publicly. So far it has not produced a charge.

Wolters admits that prosecutors must eventually risk using the evidence they have or abandon the case. Germany’s double jeopardy rules mean there is no second chance, they get only one shot at it.

Brueckner isn’t prepared to discuss any of this. What seems readily apparent is that Brueckner likes to be in control.

He hates being interrupted. I try to butt into one of his interminable rants, but he barks: ‘Listen, don’t say anything.’

And then he just carries on, protesting his innocence, repeatedly insisting he’s being framed, while imploring me not to mention any of his crimes in my article.

He even tells me how to write up this interview, then demands he is allowed to approve it before it is published (of course that did not happen). His persecution complex knows no bounds.

And though he can talk in micro-detail about what witnesses have said when they testified against him, he never shows a flicker of emotion when I mention the suffering they allege.

‘I sat there in court and just couldn’t believe how cold the prosecution were being towards me all the time,’ he says.

I pointed out the judge, Ute Insa Engemann, who acquitted him last year, was aggressive when questioning prosecution witnesses. Indeed, the prosecution argued Engemann was so biased against them that they even filed an official motion to have her removed.

Particularly questionable, they argued, was when she lifted the official arrest warrant for Brueckner during the trial.

After all, under German law, an arrest warrant can be issued only when the evidence against the accused is deemed sufficient. By revoking Brueckner’s arrest warrant, the judge had therefore silently issued a non-guilty verdict – even though the trial had not even ended. But particularly unsettling was not just the judge’s frequent red-faced screaming – rather the breathtakingly shocking words she used.

These included, for example: ‘But I don’t understand why you can’t answer – are you not able to on an intellectual level?’

And the judge was also shockingly impatient and confrontational with the young Portuguese girl who was just a child when she alleged she was forced to watch Brueckner masturbate.

‘Do you know what masturbation is?’ she snapped. ‘Yes? Then show me! How is it done? Show me now! Show me with your hands.’

Within just a few minutes of this brutal interrogation, the girl broke down in tears.

Clearly, I suggested to Brueckner, the judge had a job to do but did he not think her manner unacceptable?

‘No. She was extremely fair,’ he says. ‘She just knew that all of these charges against me were ridiculous and that there was no quality evidence against me, and so that made her agitated. It was all just a big show against me to make me look like the bad guy.’

I ask if he can relate, on some emotional level, to the suffering of these victims – especially having sat through the testimony of, for example, Hazel Behan, brutally raped while working as a holiday rep in Portugal in 2004.

‘You say victims, but they’re not my victims. These are people who have tried to get me in prison – to keep me in prison, even though I’ve done nothing wrong.

‘Yet you want me to feel sympathy for these people?’