Last week, Elon Musk appeared at a Donald Trump rally in Pennsylvania, jumping up and down and telling the crowd that the November vote was the ‘most important election of our lifetime’.

The billionaire founder of Tesla and SpaceX and owner of X/Twitter has become a key figure in US politics in recent months, as he throws his weight behind Trump in his quest to retake the presidency in November.

Musk has long publicly styled himself as a free-speech absolutist, telling his 200million Twitter followers that free speech is the ‘bedrock of democracy’ and that anyone trying to silence another person is a ‘liar’.

But my new podcast investigation called Elon’s Spies reveals how Musk, or those working on his behalf, have used private investigators and surveillance tools to control information and suppress critics.

And one of his prime targets has been Vernon Unsworth, the British cave explorer who helped rescue 12 children from a Thai cave in 2018.

At the time, the Tesla billionaire called Unsworth a ‘paedo guy’ on Twitter after the caver criticised his plans to help with the rescue.

‘It’s the most disgusting thing that you can call anybody, really’, says Unsworth.

Although Musk eventually apologised, the baseless slur hangs over the financial consultant to this day.

‘I’ve not spoken to anyone in depth about Musk or the effect it had on me,’ he says. ‘I’ll be tarred for the rest of my life. When I went to receive my MBE from the Queen back in June 2019, the headline next day was all about Musk. The stigma is always there.’

Extraordinarily, Musk’s surveillance targets are also understood to include Amber Heard, his former partner.

In 2017, when the couple were dating, Musk’s security team is understood to have employed an Australian private investigations firm to monitor Heard’s movements when she was filming Aquaman on the Gold Coast.

The surveillance is said to have been extensive and to have involved multiple operatives as well as infrared cameras and drones. Musk did not respond to requests for comment on this or other allegations. But more on that later.

For the Unsworth case is, in many ways, the most shocking.

On June 23, 2018, a group of 12 boys, aged 11-16, and their 25 -year-old soccer coach went to explore the Tham Luang cave system in northern Thailand. They didn’t come out. Rising flood water after heavy rain had trapped them inside.

Unsworth, 69, who lives between Thailand and the UK and who had explored the Tham Luang cave before, was one of the first on the scene. ‘I arrived very early on the morning of the 24th,’ he says. ‘It all started from there.’

Soon the cave’s mouth was crowded with people trying to help, including a group of Thai Navy Seals.

But Unsworth knew the very people who could be key in effecting a rescue and passed a note to the Thai authorities with the names of ‘the three people’.

The next day, British cave-divers Richard Stanton and John Volanthen, and British caver Robert Harper, arrived at the scene.

‘The four of us had between us over 150 years of caving experience,’ Vernon remembers. ‘The problem was that all the Navy Seal command saw was four old guys… dressed in scruffy T-shirts and shorts.’

Despite their dress sense, the British cavers came up trumps. On July 2, Volanthen and Stanton found the boys alive, huddled together on a muddy slope about three miles into the cave system. But the biggest challenge remained: getting them out.

An audacious plan was put in place to anaesthetise the boys using ketamine, equip them with breathing apparatus and take them out while unconscious. It worked. By July 10, all the boys and their coach were rescued alive.

‘Obviously I was proud to be part of what happened,’ Unsworth says. ‘Because I don’t think many people gave the boys much of a chance.’ He’s underselling it. According to the other divers, if it wasn’t for him, the boys would be dead.

It was the happy ending everyone hoped for. Except that the story of the trapped boys didn’t go unnoticed by Elon Musk.

Days into the rescue attempt, he announced that he would build a ‘tiny, kid-sized submarine’ to bring the children out. It was a typically bold move by the swashbuckling billionaire. A consequence of a mindset that says every obstacle is just an engineering problem waiting to be solved.

To Unsworth, Musk’s submarine was completely impractical. When he was asked about it by a CNN reporter, he didn’t mince his words. ‘He can stick his submarine where he hurts,’ said Unsworth, a self-described ‘brash Northerner’.

Elon Musk is not someone to let an insult lie. In a series of tweets that he later deleted, Musk called Unsworth a ‘paedo guy’. A few days later, Musk apologised. But then he posted another tweet, implying that the reason Unsworth hadn’t sued him yet was because the allegation was true.

In August, 2018, Musk emailed Ryan Mac, a reporter at Buzzfeed News, claiming without evidence that Unsworth was a ‘child rapist’ who had moved to the south-east Asian country to take a child bride.

‘He’s an old single white guy from England who’s been travelling to or living in Thailand for 30 to 40 years,’ Musk wrote. ‘I fucking hope he sues me.’

Unsworth did, in fact, go on to sue Musk in the US but lost the case after Musk’s lawyer portrayed his tweets as ‘a joke’.

Unsworth didn’t know it at the time, but Musk had been fed ‘information’ on Unsworth by a private investigator called James Howard Higgins. A British man who said he’d worked for tycoon George Soros, Howard Higgins had been engaged by Musk’s right-hand man, Jared Birchall, a few weeks before. Emails between Howard Higgins and Birchall show how Howard Higgins was prepared to go to almost any lengths to get the information Musk wanted.

He promised to go through Unsworth’s bins, to put him under 24/7 surveillance, to infiltrate his partner’s Facebook account and to pose as a charity worker to get information. He even said he had inside information on Unsworth’s British legal team, including the name of the lawyer representing the caver.

Mark Stephens, Unsworth’s British lawyer, told me that these techniques, if they had been implemented, were ‘pretty obviously unlawful’. Musk is understood to deny any wrongdoing.

James Howard Higgins was, in fact, a fraudster. Almost every bit of information he passed back to Musk about Unsworth was false.

For instance, far from having spent decades in Thailand and marrying a ‘child bride’, Unsworth had first visited Thailand only in 2011 and met his partner, Tik, when she was in her 30s.

If Birchall or Musk had simply Googled Howard Higgins’s name before hiring him, they might have seen that he was jailed in 2016 for stealing from his own company.

At Unsworth’s defamation trial against the Tesla founder, Musk’s team portrayed Howard Higgins as a one-off – a fraudster who had scammed a billionaire. In fact, our investigation reveals that Musk tasked a second investigation firm to get information on Unsworth.

In August 2018, Orion Investigations emailed one of Unsworth’s friends, making ‘discreet’ inquiries about the caver. Orion’s representative assured the friend, incorrectly, that he was ‘working on behalf of Vernon’.

In fact, evidence suggests Orion’s ultimate client was Musk. Unsworth now wants answers. ‘Musk needs to reveal exactly what surveillance he used on me: which firms, and what methods,’ he says. ‘His defamation still hangs over me six years later.’ Musk, so far, has declined to comment.

Unsworth was far from the only individual targeted by Musk, however. Several former Tesla employees also allege they witnessed surveillance. Karl Hansen, a former security executive at Tesla’s Nevada gigafactory, told me that he believed Musk’s team hacked into the phone of a Tesla employee called Martin Tripp, whom Tesla suspected of speaking to the press.

Evidence filed by another security executive, Sean Gouthro, in a case brought by Tripp against Tesla appears to substantiate some of Mr Hansen’s account.

Gouthro says external private investigators followed Tripp ’24 hours a day’. In a video deposition, Gouthro says he witnessed what appeared to be Tripp’s emails and personal text messages being accessed in real time.

‘There was a delay, but you could see the text messages coming in,’ he said. ‘Emails, notification bars popping up. The name of his wife was brought up. We saw pictures of his kids.’

Tesla strongly denies that any hacking or any illegal or disproportionate activity took place. The company has said Gouthro was let go for poor performance, including ‘repeated failure to demonstrate and understand best practices in the security industry.’

But perhaps the most unexpected accusation to emerge from my investigation concerns Amber Heard, Musk’s one-time partner.

According to sources, Musk suspected Heard was cheating on him during a period in 2017 when she was filming the movie Aquaman on the Gold Coast in Australia.

I’ve been told that Musk’s security team contacted a well-known Australian investigations firm, specialising in infidelity, who put Heard under surveillance for weeks, if not months, at a cost of more than AUS$100,000 (£51,000).

According to my source, the investigation apparently spared no expense and involved infrared cameras and drones. If the operatives were ever caught, they were allegedly told to pretend they were paparazzi.

During Heard’s stay on the Gold Coast, the city’s local newspaper received an anonymous tip that an Aussie Rules footballer was ‘spending many nights at Amber Heard’s house’ and ‘leaving early in the morning looking like the cat that swallowed the canary’. At the time, Heard’s address was not public knowledge.

The paper traced the message to SpaceX, one of Musk’s companies. When Sally Coates, one of its reporters, spoke to Musk on the phone, he accepted that someone close to him had sent the tip but claimed it was done without his knowledge. Heard and Musk both declined to comment.

Alexi Mostrous is head of investigations at the media group Tortoise. Elon’s Spies (https://lnk.to/ElonsSpies) is now available wherever you get your podcasts. Listen to all three episodes today by becoming a Tortoise+ member on Apple podcasts or downloading the Tortoise app.