Reports of the Tromp family’s sudden flight from their home, and their discovery one by one in confusion and distress, gripped the public imagination. How much do we know, and how much have we a right to know? By Martin McKenzie-Murray.

The Tromp family’s crisis

It was a decade ago that the Tromp family moved to their Parkview farmstead in the lush and fertile Yarra Valley. The town was Silvan, which was Chapman country, a family who had begun farming the area at the turn of the 20th century. The Tromps’ neighbours were Chapmans; their street bore the same name. Later, when the family experienced their mysterious crisis and the imagination of the country flared, it was a Chapman who publicly offered surprise and sadness at their plight. “They are excellent people,” Mark Chapman told the Herald Sun. “Honest and hardworking people. This whole thing is very distressing. There was nothing, no sign that anything was wrong.”

Mark Tromp and his wife, Jacoba – she prefers “Coby” – are the parents of three adult children, Mitch, Ella and Riana. Four of the five lived on the property, helping farm the hectares of redcurrants and the side business of lending farm machinery. Like other berry farms in the area, the Tromps ran a “u-pick” service – the public could buy meditative time on the farm and pluck their own produce to take home.

A former teacher, Coby had been introduced to redcurrant recipes by local chefs when they moved in. She learnt how to make preserves, selling them to cafes and restaurants and offering recipes on their business’s website. The children were sociable and hardworking. They had many friends; they travelled. Ella was an equestrian, and had grown close to her horse Biggles. Their uncle, Mark’s brother, was a police officer in a nearby town.

It appeared to be an entirely normal existence, the tranquil landscape contrasting with their strong work ethic. It was also an entirely private existence, until last Monday when the five of them piled into a silver Peugeot and created what a local police officer described as “the most bizarre case in 30 years”.

What is known

Local police found the Parkview homestead to have been abandoned in dramatic haste. The home was open and financial records were meticulously stacked on tables. Their mobile phones and credit cards were left behind. Each family member’s passport was out, suggesting a flirtation with international departure. Police were left with a variation of the Mary Celeste ghost ship mystery – what induced a family to abandon what appeared to be a healthy and uncomplicated existence? A local police sergeant who knew them said they were regular folk, neither cult members nor drug users nor the subjects of terrible debt.

Before they got into the car, Mark Tromp feared for their lives. The children were ordered by their father to abandon their electronic devices – they might be used to track their capricious journey. Then he drove. And drove.

We know that the Tromp children were alarmingly confused. We know that Mitch had smuggled his mobile phone aboard, only to throw it from the moving vehicle when his father discovered its presence. We know that Mitch could only describe his parents’ erratic behaviour as being “like a movie”.

We know that Mitch left the car first. We don’t exactly know why, or how he excused himself, but evidently it became too much. Mitch left on the second day of the trip in Bathurst, a New South Wales town some 770 kilometres north-east of Silvan. He made his way back to the farm via trains and buses. There followed a bizarre separation of the remaining passengers.

We know that Mark Tromp continued on to Jenolan Caves in NSW’s Blue Mountains. The caves are a series of ancient limestone formations, and popular with tourists. They’re an hour’s drive east from Bathurst, and we know that it was here the two daughters left the car and tried to make their own desperate way back to their farm. We know that police have alleged that to fulfil that desperate journey, Ella stole a car and Riana joined her. We know that the NSW Mental Health Act has been invoked to drop the charge against Riana, and we know that there’s little likelihood the outstanding charge against Ella will make its way to court.

We know that the two sisters then made their own road trip, riding together until they hit the NSW town of Goulburn, some 150 kilometres south of the caves. Riana left the car, and secreted herself in the empty cabin of a stranger’s ute. Ella continued south to the Victorian border and, beyond that, home. She needed to feed her horses, she later said.

We know that the driver of the ute was startled mid-trip by the presence of Riana, who was squished within the foothold behind his seat. Shocked, he pulled over and found her in a “catatonic state”. She offered $50 for his trouble. He offered to call authorities, and she was taken to Goulburn hospital where she was examined by mental health doctors and, at time of writing, where she remains.

We know that a few days into the drive, there remained only the parents. We know that Coby was the next to abandon the car, leaving only her husband behind the wheel. Coby was found by a passer-by in the town of Yass – not far from Goulburn – wandering the streets in an agitated state. She was taken to Goulburn hospital, where she also remains at time of writing.

In the silver Peugeot there now remained only Mark Tromp. We know that within the vicinity of Wangaratta, a Victorian town some 350 kilometres south of Yass, Mark was attracting attention. We know that a couple, out driving to collect Pokémon, reported a man alarmingly trailing their car. He was uncomfortably close, and when they pulled over to the side of the road, he did the same. We know that they reported the driver getting out of the car and wandering strangely in the road. When police were called, he abandoned his car and fled into a park. Police dogs and officers couldn’t immediately locate him. Mark Tromp had vanished.

We know that from this point there was national media attention. There was a police operation that stretched two states and organised to locate Mark Tromp. We know that among this there was a flurry of speculation and red herrings. We learnt of a series of local burglaries, and heard of erroneous sightings in Bega. More pointedly, we knew there was a family desperate to have their father found alive and safe. Almost a week after they left the Silvan farm in the silver Peugeot, he was found on the outskirts of Wangaratta. It was the day before Father’s Day.

Public curiosity

That the mystery was so beguiling, comprising so many head-scratching elements, distracted from the fact that this was a family experiencing a terrible crisis. Their rightful desire for privacy was made clear in a press conference, conducted not long after their father was found. This appearance, of Mitchell and Ella Tromp, protectively maintained rather than relieved the mystery. “I can see everyone’s questions,” Mitchell said on Sunday. “I can see why they want to know, but it’s a family matter. We just want the family to come back together and everything to sort of work itself out, and I think it will.”

The siblings – the public face of the family – had a sister and a mother in hospital and, until Saturday, a father who had vanished in alarming circumstances. We only had questions.

Those questions were breathlessly responded to with speculation: murder or mob debt, drug-induced psychosis, a nefarious cult, or the unwitting ingestion of a natural toxin. Police were quick to extinguish most of these. What remained was a curiosity so intense that we somehow felt entitled to resolution.

In a leaked brief circulated internally by NSW police, the words “shared delusional schizophrenia” appeared. It gave the clearest clue yet to the mystery, even if it is clinically impossible to “share” schizophrenia outside of genetics. What those words suggested was the disorder of “shared psychotic disorder” or, in its original form, folie à famille, whereby the symptomatic delusions of a schizophrenic are emotionally communicated to intimates.

Shared psychotic disorder

In the late 1970s, a distraught family presented their six-year-old daughter to a psychiatric clinic in Los Angeles. They sought an examination, and a solution, to the bizarre behaviour of this little girl named Mary. Her family – middle-aged parents, an 18-year-old sister and a 12-year-old brother – told doctors they were bewildered by Mary’s tendency to fake mental impairment in public. The malingering often appeared as a refusal to speak, whereas at home she was brilliantly verbal and responsive. The ruse was sufficiently elaborate to suggest a superior intelligence, one peculiarly applied to pretending its opposite.

The family was at a loss, and each member gave earnest testimony about her behaviour at home. “She’s a really fast child, if anything,” the father said to doctors. “I’ve had 10-minute-long normal conversations with her, but she won’t talk in front of most people,” offered her sister.

For two months, Mary was observed 24 hours a day, five days a week. Her family took her home on weekends. She was examined by psychiatrists, psychologists and paediatricians. She was seen by dentists, nurses and neurologists. After eight weeks, the experts were unanimous: Mary was “severely retarded”. She was not toilet trained, had mild cerebral palsy, and an approximate IQ of 20. Her height and weight were alarmingly below average, and she had the verbal development of a nine-month-old.

This wasn’t the first time Mary’s family had received this appraisal. They had visited two clinics previously and been told the same. But Mary’s family had developed a shared delusion about her health, and had artfully maintained it for more than half a decade. The findings of the latest clinic couldn’t dent it, and they insisted upon Mary’s gifts and the doctors’ gullibility. A therapist at the Los Angeles clinic made the rare diagnosis of folie à famille.

What today we might diagnose as shared psychotic disorder was originally described by French therapist Jules Baillarger as folie communiquée, later described in the psychiatric literature as a psychosis by association. The term folie à deux – or a “madness of two” – is a more enduring description, coined by psychologists in 1877.

It is little studied, and case examples appear relatively rarely in psychological papers. It is respected that folie à deux is rare, and the larger contagion of folie à famille rarer still. In the past it has appeared in the Diagnostic and Statistical Manual of Mental Disorders as “shared psychotic disorder”, and in the International Classification of Diseases as “induced delusional disorder”.

What most of the literature agrees on is it entails an influential family figure, struggling with a mental disorder, imposing his or her delusions upon his or her intimates. Qualities of social isolation and personalities that are suggestive and malleable to the inducer’s delusion often appear, but are not consistent.

Within this scientific literature, there is the example of an Austrian family, close-knit and educated, who contradicted the belief that those experiencing folie à famille were socially estranged. The husband and two adult children seemed to revolve around their mother – charming, voluble and highly protective of them. Over time, what began with her irritation at the neighbours’ noise – they lived in the apartment upstairs – devolved into an intricate delusion: that the neighbours were conspiring to poison her family with electronic radiation. An increased power bill supported her suspicion, as did twitching legs and a constant state of fatigue. Eventually, the husband, sons, a sister-in-law and nephew were conscripted into the delusion. Each began to experience the twitching and fatigue. Each had difficulty sleeping. In the summer of 1985, the family installed a microphone in the ceiling, hired a private detective and sought advice from a friend who worked in the secret service.

The delusion dissipated after the sons left the house, and therapists observed “dramatic improvements ... after environmental manipulation only”. That is, when they left the house and distanced themselves from the mother.

A more recent example featured in a 2010 volume of the Indian Journal of Psychiatry. The authors of the paper first encountered the family when a 40-year-old man was brought by police to the hospital where they worked. He was diagnosed with paranoid schizophrenia – a condition that had been untreated for its approximate four years – as well as antisocial personality disorder and alcohol abuse. He was gripped by the belief that his neighbourhood was filled with enemies intent on killing him and his family.

The man had gravely isolated his wife and three young children. Unemployed for four years, the man forbade his family from leaving the house in that time. The doctors found the wife and three children had no history of mental illness, but in the past year had begun to demonstrate the same persecutory delusions as the father. Now hospitalised, the man was prescribed anti-psychotic medication and remained in hospital for two months. In that time, the remaining family – who visited him only twice – experienced a weakening of their delusion. “This case demonstrates a case of folie à famille,” the doctors wrote. “In the above family, [the father] was the dominant person who was suffering from schizophrenia and had [the] prominent delusion of persecution while other members of the family received a diagnosis of shared psychotic disorder... The patient was imposing his ideas on his family ... The family passively submitted to and shared the imposed delusional system of the patient. They did not have any other primary psychiatric diagnosis.”

How delusion can spread

During early evaluations of Mary, the little girl in Los Angeles, experts watched through a two-way mirror as her family interacted with her. The family were provided with various playthings – balls, blocks – and their interactions with her were recorded. What the experts witnessed was a family artfully maintaining their delusion: if Mary didn’t offer the ball upon request, it was interpreted as refusal rather than obliviousness. Or they witnessed the family conduct what the therapists called “commanding the already done”. After observing Mary begin an action – lying on the floor, for example – the family would request that she remain there, maintaining the “aura of competence”.

This cognitive waltz was perpetual – the family were forever framing and interpreting actions in such a way as to entrench their delusion. They imagined playfulness, mischief and verbal ability where there was none. The authors of the report likened the process to an ancient Zen story, whereby a novice asks his Zen master to draw a perfect circle. The master obliges, and in the sand before him renders a crude oblong. “That isn’t a perfect circle,” the novice says. “No,” the master replies, “but it is a perfect whatever-it-is.”

While Mary was under observation, her family appeared to suffer a dramatic disintegration. Within two weeks, her 42-year-old father, with no observed history of cardiac illness, suffered a major heart attack. He survived, but was hospitalised for weeks. During his convalescence, his teenage daughter severed three fingers in an industrial accident. Not long afterwards, the son experienced blackouts and hives and was removed from school.

It emerged that the family had lost their 12-year-old son to drowning when Mary was 18 months old, and to facilitate healing had moved to live in another state. This only served to isolate them, and the father’s emotional dependence on his wife – who was diagnosed as “borderline psychotic” – grew deeper. It was not long after this move that the family began reporting Mary’s “bizarre” behaviour. The therapists reported that “the precipitating events were probably the son’s death, the awareness of Mary’s developmental delay, the mother’s depression, the father’s professional failure, the financial strain, and the move to a new location”. In other words, it was a family enduring terrible stress and sorrow.

Diagnosis unreliable

In the Indian case study, the father was said to have imposed his own beliefs upon the family – which is not dissimilar to what I have done here to the Tromps. It’s a dubious exercise.

Police quickly ruled out impropriety and now state that they don’t foresee any charges beyond the one of car theft, and that charge isn’t expected to reach court. I was told early that the family “weren’t crooks” but, beyond that, police were as puzzled as anyone. Which is odd, because police can normally be relied upon to have a theory about anything. It’s a function of cynicism, and of their own hard experience with the patterns of human foible. But with the Tromps, there was no precedent, only anomaly.

There are also questions regarding shared delusional disorder itself. I asked a professor of psychiatry if he knew of any experts in this exotic pathology, and he was admirably blunt in his response. “Sorry, but I’ve no idea at all,” he wrote. “As you say, it’s exotic – to the point where I’ve never heard of it and suspect many of us would doubt its existence, I think. Even folie à deux, involving just two people, is extremely rare. I’ve never seen that, and certainly nothing resembling a shared family delusional system of the kind being proposed.”

It is argued that cases of shared delusional disorder – especially those rarely experienced by families – are so complex and varied in their causes as to render a stable designation absurd. A family’s dynamics might be so idiosyncratic as to resist uniform description. And those dynamics may be informed by an external environment – severe political oppression, for instance – in which paranoia might be an entirely useful and legitimate response. There may also be genetic determinants, untested and unknown to historic studies. 

Shared psychotic disorder appeared in the Diagnostic and Statistical Manual of Mental Disorders for the first time in its fourth volume, published by the American Psychiatric Association in 1994. In the latest edition, DSM-V, published in 2013, it vanished as a discrete disorder, and was folded in with the general “delusional disorder”.

But while the DSM is often referred to as a diagnostic bible by laypeople, it is not fixed, infallible or uncontested. Nor is it the sole bible. There is, for example, the International Classification of Diseases, compiled by the World Health Organisation. The current list includes induced delusional disorder, described as “a condition in which closely related persons, usually in the same family, share the same delusions”.

All of which is to say, we do not know, and perhaps that’s fine.

How curiosity can obscure judgement

Last week I felt – like a lot of people, I suspect – that an answer was inevitable. The Tromps’ exposed paperwork itself provided sufficient clues, didn’t it?

That sense of inevitability assumed the Tromps’ rightful place in our public imagination; perhaps even an entitlement to answers. As a journalist, I cultivated my curiosity on behalf of others. On Facebook, people invoked the “taxpayer” – the noble financier of the police search – as grounds for demanding a public confession.

But a confession of what? As suggestions of crookedness were dismissed by authorities, we were left with something very private. Police told me the family had declined their offer of media support, provided to families overwhelmed by public attention. The Father’s Day press conference was intended as a chance to feed the media’s appetite, before retreating to privacy. The children were grateful for their father’s discovery, but now found the media could only serve as a terrible invasion. I had a mobile number for the family. Friends told me to leave them alone. I had already tried the number.

Our curiosity turns people into puzzles to be solved, and people like me assume the role of solving that puzzle for readers’ entertainment. We can sell it as something more important, as a story that tells us about ourselves, about our humanity, but rarely do these things add up to more than what they are. We might grasp – and I write this to myself mostly – that this is not our mystery to solve.

This article was first published in the print edition of The Saturday Paper on September 10, 2016 as "Shared intrusion".

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Martin McKenzie-Murray is The Saturday Paper’s associate editor.

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