Every time I think I've seen it all when it comes to American gun violence, something happens to snap my eyelids back with stunned bemusement.

In the early hours of yesterday morning, a half-naked 29-year-old man named Travis Reinking opened fire with an AR-15 semi-automatic rifle on customers in and outside Antioch Waffle House in Nashville, Tennessee.

He killed four people and wounded another four, before unarmed heroic bystander James Shaw (note to the NRA: a good guy without a gun) confronted him and wrestled the gun away.

Travis Reinking, 29, shot dead four people and injured seven others at the Waffle House in Antioch early Sunday morning before an unarmed hero wrestled the gun away

None of that, though, is the incomprehensible part of this horrific incident.

Let's be horribly frank: a crazed young man committing a mass shooting in the US with an AR-15 is almost a weekly occurrence these days.

No, what is utterly staggering is how he came to be in possession of his gun to commit his heinous crime.

For Reinking is a complete lunatic.

And a self-evidently dangerous lunatic.

I don't say this lightly, or to infringe on his human rights not to be called a lunatic in case it hurts his feeling.

I say it because it's an incontrovertible fact.

In May, 2016, an ambulance was called to a CVS parking lot after Reinking threatened to kill himself. His family told deputies at Tazewell County Sheriff's Department in Illinois he was having paranoid delusions that music superstar Taylor Swift was stalking him and hacking his phone and Netflix account. He also believed his parents and police were involved.

Reinking himself told police Swift had wanted to meet him at a Dairy Queen and when he went there, she screamed at him across the street then ran away.

He said he chased her 'to stop her harassing me', then followed Swift up the side of the building and onto its roof but when he got there, she had gone.

Reinking was taken to a local hospital for an evaluation 'against his will', according to the report.

In May, 2016, an ambulance was called to a CVS parking lot after Reinking threatened to kill himself. His family told deputies he was having paranoid delusions that Taylor Swift was stalking him. He was taken to a local hospital for an evaluation 'against his will'

His family told police he had suffered similar delusions since August, 2014. 'Travis is hostile towards police,' they said, 'and does not recognise police authority.'

In June, 2017, Reinking jumped into a nearby community swimming pool wearing a pink woman's coat over his underwear and began threatening lifeguards, urging them to fight him and then exposing his genitals.

The same day, an employee at a construction site owned by the Reinking family told police he had a yelling match with Reinking, who had showed up in the pink coat with an an AR-15 in his hand and shouted 'Is this what you f***ing want?' before putting the gun back in his car and speeding off. No charges were filed, but the Sheriff's Department advised members of Reinking's family to take away his guns and lock them up until he got some help.

A month later, on July 7, 2017, Reinking pitched up at the White House demanding to meet President Trump. He crossed a restricted area and approached a Secret Service agent, saying he had to get inside and instructing the agent to 'do what you need to do, arrest me if you have to.' He was duly arrested, charged and later ordered by the D.C. Superior Court to do 32 hours of community service. Oh, and he was told to stay away from the White House.

On August 11, 2017, Reinking spoke with a Tazewell sheriff's deputy and claimed that dozens of people were tapping into his computer and phone and people were lurking outside his home 'barking like dogs'.

Following the White House incident, the FBI requested that police in Illinois revoke Reinking's state 'Firearm Owners Identification' card and seize his four weapons.

These were a Kimber 9mm handgun, a CZ-USA .22 rifle, a Remington 710, and the Bushmaster AR-15 rifle he used at the Waffle House.

Reinking gave them up to the Tazewell County Sheriff's Department on August 24, 2017. But deputies returned the guns to his father Jeffrey after he promised to 'keep the weapons secure and away from Travis.'

Today, Nashville police spokesman Don Aaron said Jeffrey Reinking had admitted giving the guns back to his son.

After a string of crazy incidents, including Reinking showing up at the White House demanding to meet Trump, his guns were confiscated. But deputies returned the guns, including this AR-15 used at the Waffle House, to his father Jeffrey after he promised to 'keep the weapons secure and away from Travis.' But Jeffrey gave the guns back to his delusional son

This despite him telling police he often locked up his son's rifles when 'Travis was having problems.'

Nobody yet seems to know why Mr Reinking would therefore give them back to his son, knowing his state of mind.

I'd like to know why the hell he did that. Urgently.

But more importantly, I'd like to know why the Tazewell County Sheriff's Department thought it was a good idea to return Travis Reinking's guns in the first place?

'There's certainly evidence that there's some sort of mental health issues involved,' said Tazewell sheriff Robert Houston, in what you might conclude is the understatement of the century.

Yet he insisted officers did not believe they had any legal authority to withhold the weapons.

Sorry?

All due respect Sheriff - what the **** are you talking about?

How many more red flags was this loon supposed to wave at you?

Travis Reinking had revealed himself over a period of several years to be a paranoid, delusional, threatening, police-hating, gun-toting, potentially very dangerous whackjob.

The FBI told you to seize his guns after he tried to storm the White House to get to President Trump.

But instead, you gave them all back to his dad, who gave them back to his mad, dangerous son despite knowing he is delusional and suicidal.

The FBI told authorities to seize his guns but police gave them all back to his dad, who gave them back to his mad, dangerous son despite knowing he is delusional and suicidal. Travis Reinking then used one of those guns to commit mass murder on a random selection of innocent people eating at this Waffle House

Travis Reinking then used one of those guns to commit mass murder on a random selection of innocent people eating at a Waffle House.

I'm sure this all makes perfect sense to NRA supporters.

After all, Jeffrey Reinking had his own firearms certificate, so he was a 'responsible law-abiding gun owner' – right?

That's why he was allowed to take back his son's guns.

No. He was woefully, criminally irresponsible.

But so were the police, who should have done what the FBI told them to do and seized the guns.

Giving them back was as insane as what they KNEW to be the disturbed dangerous state of Travis Reinking's mind.