Looking back, they had known – perhaps for a long time – that it might end like this. With hindsight, says Matthew Caruana Galizia , red-eyed from emotion and lack of sleep, it seems obvious. “This wasn’t an aberration,” he says. “It was a culmination.”

The air in the family home in the hamlet of Bidnija, half an hour’s drive from the Maltese capital, Valletta, is thick with grief and quiet anger. Police guard the entrance to the gravel driveway and the cast-iron gates in front of the house.

Matthew, his brothers Andrew and Paul, and their aunt Corinne sit on the sofa and a couple of old armchairs around a large, low table filled with empty coffee cups. It is a warm, comfortable, lived-in room; on another day, you might admire the view.

But outside, down the hill a few hundred yards away and just visible from the end of the drive, a blue and white marquee stands in the middle of a field. Figures in white overalls comb the ground around it; the road beside it is closed to traffic and lined with police cars and vans.

The marquee covers the remains of the Peugeot in which the brothers’ mother and Corinne’s sister, the investigative journalist Daphne Caruana Galizia, was killed on Monday afternoon in an explosion so powerful that it blew the car, in pieces, into the field.

“I was sitting at the table there,” said Matthew, himself a Pulitzer prizewinning investigative journalist. “I heard the explosion; the windows rattled, the whole house vibrated. I knew she was dead before I got up from my chair.”

Daphne Caruana Galizia had made many enemies in the 30 years since she first began skewering alleged high-level corruption in Malta’s political, business and criminal elites – often, she would argue, one and the same, or at least closely connected – in print.

Forensic experts search for evidence on Wednesday following the death of Daphne Caruana Galizia.

Photograph: Darrin Zammit Lupi/Reuters

In recent years her hugely popular blog, Running Commentary, had attacked Malta’s prime minister, Joseph Muscat, his chief of staff, Keith Schembri, and Konrad Mizzi, the then energy minister, tying offshore companies allegedly linked to the three men to the controversial – and highly lucrative – sale of Maltese passports and large payments from the government of Azerbaijan.

But the targets of her cutting, sometimes savage posts covered the full spectrum of graft, cronyism, corruption and organised crime, taking in politicians (including from the opposition), banks aiding money laundering and tax evasion, online gaming firms infiltrated by the mafia and drug smugglers.

Much of her – and Matthew’s – work since last year had focused on revelations from the Panama Papers, a huge cache of leaked documents from the leading offshore law firm Mossack Fonseca. But long before then, her sons recall, she was being relentlessly harassed and intimidated.

“In 1996, the front door was set on fire,” says Andrew, who works now in the Maltese diplomatic service. “Around about that time, too, someone killed the dog – cut its throat and laid it across the doorstep. A few years later, the neighbour’s car burned out; his house has almost exactly the same name as ours.”

The most serious attack before Monday’s fatal car bomb was in 2006. Paul, now a fellow at the London School of Economics, was coming home late, around two in the morning, and saw “a huge blaze, right beside the house. They’d dumped two big stacks of car tyres, filled them with petrol, and set light to it.”

Paul reached the house just in time to stop the fire taking hold of the building and to wake his parents, who were asleep inside, oblivious. “That was the first really serious attempt to physically harm her,” Paul says. “The clear intention was to burn the house down, with her inside it.”

Death threats were almost a daily occurrence, says Matthew: “We grew up with them. Phone calls, letters, notes pinned to the door. Then when mobile phones arrived, text messages. And later of course, emails, comments on her blog. Not to mention the lawsuits. So many lawsuits.”

There was “a concerted attempt to ruin her financially”, adds Andrew. “The libel threshold in Malta is low, and to respond – simply to say you’re contesting it – you have to pay something like €900 into court. They came at her like that in groups, businessmen, politicians, often with foreign lawyers.”

Candles are lit in memory of Malta’s Daphne Caruana Galizia in Brussels, Belgium on Wednesday. Photograph: Yves Herman/Reuters

This year alone, says Matthew, counting off the names on his fingers, “15 – no, maybe even 20 people” filed for libel against his mother. One guy, a wealthy businessman, “filed 19 suits, one for every sentence in one of her articles”.

With the support of their father, her husband Peter, a “completely unflappable” lawyer, Daphne Caruana Galizia nonetheless gave her sons “a normal childhood”, says Matthew. “We were her priority, always,” he says.

“But she remained capable of outrage. That’s the thing. She never, ever became cynical. Despite all she knew about everything that’s rotten in this country, she never became cynical.” And there are things about Malta, this family now knows, that smell very rotten indeed.

They outline, in detail, cases of investigations not pursued, of reports suppressed, of honest law enforcement officials threatened and inquiries quashed, on the orders of politicians.

“There has been,” says Matthew, “a takedown of the rule of law here. There has been capture of the state by corrupt and criminal corporations. The institutions do not work. There is a climate of impunity.”

In recent years Malta has been called a “pirate base for tax avoidance”, helping multinational companies dodge nearly €15bn in tax. Organised crime, including Italy’s ’Ndrangheta, uses one of its major industries – online betting, which accounts for 10% of the island’s GDP – for large-scale money-laundering, according to Europol.

The country’s biggest source of revenue is now selling Maltese citizenship and passports, which cost €650,000 each, to very wealthy foreigners. In the past 10 years, it has witnessed 15 mafia-style killings, including five car bombings in the past two years. All in a member state, the smallest, of the EU.

Daphne’s family are not confident her death will change any of this. “It will take other people,” says Matthew. “Part of what led to this is that no one else did anything. They shrugged their shoulders. In a normal country, a failure of the state would be recognised, the institutions of civil society would move in, fix things. But what can move in here? This is not a normal country.”

The wreckage of the car belonging to Daphne Caruana Galizia. Photograph: Rene Rossignaud/AP

In Malta, says Paul, the prime minister appoints the magistrates, the police commissioner, the justice minister and – jointly – the attorney general. “This is an institutional problem,” he says. “There aren’t the normal checks. Here, if the government doesn’t want to be investigated, it won’t be investigated.”

So their mother’s death, say her sons, was not an isolated attack on freedom of expression, but a symptom of something else: a system. “These things don’t happen by accident,” says Andrew. “This state of affairs was cultivated. If a journalist dies, it’s because people are not doing the job they’re supposed to do.”

Other people, adds Corinne, need to step up now. “Everyone – including other journalists, media we know are sitting on big stories – needs to do their job. Malta has become the useful tool of international criminal networks, and there was just one nuisance, my sister, telling everyone it was happening.”

It is important, of course, that Daphne Caruana Galizia’s killer – or killers – are found. But in a way, says Matthew, “it’s almost irrelevant. So many people wanted her dead, so many benefit. People say, ‘I hope they find the bastards.’ But we know where the bastards are. They are in government. They’re on the TV. And they all, in part, bear responsibility.”

