‘They tend to be kind of sneakier’: Profile of a poisoner

Joni Johnston, a US forensic psychologist, is no stranger to poisoners. She has spent a large part of her storied career researching and interviewing these types of killers, and can list their common traits like items on a grocery list: They are likely to come from a medical background, their victims are likely to be family members, and they are often motivated by revenge or financial gain.

And yet, despite her years of research, Johnston is frequently baffled by the way these types of killers can behave after committing their crime.

She has encountered several cases of poisoners who were “so sneaky” they could have gotten away with murder – if not for how they behaved after committing the crime.

“I see it over and over and over again … What I would say is, if you’re not a career criminal, if you’re not somebody who is antisocial by nature, or grew up committing crimes – it does require a mental process to get to the point where you decide to murder someone,” Johnston says.

Erin Patterson outside court during her trial.Credit: The Age

Erin Patterson did not get away with her crime. The 50-year-old was found guilty this week of murdering her in-laws, Don and Gail Patterson, and Gail’s sister, Heather Wilkinson, and attempting to murder Heather’s husband, Ian, by serving the elderly group a home-cooked lunch laced with death cap mushrooms in July 2023.

Patterson’s behaviour after the deadly lunch was a point of focus for the prosecution during her trial. The prosecution took the jury through the key moments that they said proved Patterson’s guilt: leaving the hospital against medical advice, throwing away a food dehydrator and factory-resetting her phone.

“They [poisoners] think up to when the murder happens, and then there’s not a lot of thought about, ‘How am I going to handle this afterwards?’” Johnston tells this masthead.

Johnston recalls a case in the US where a man aroused suspicion after he moved his mistress into the family home days after his wife’s sudden death. He was later convicted of poisoning his wife.

There was also the death of Steve Clayton. It was initially believed the South Carolina man died of a heart attack – until Clayton’s family noticed how oddly his wife, Lana, behaved in the days after his death. Investigators later discovered she had poisoned his drinking water, killing the 64-year-old.

Now, after one of the most closely watched murder trials in Australian history concluded this week, experts such as Johnston are left to dissect how the mother of two fits in with the typical profile of a poisoner, and why the case garnered such frenzied, global interest.

The first point Johnston is keen to clear up is a common misconception – that more women poison than men.

“There are all kinds of stereotypes about women that have lasted throughout eternity,” Johnston says. “One of them is that women are more devious … They don’t beat you up, they don’t hit you, they just poison your food. Given the fact that 90 per cent of all murderers – at least in the US – are men, there are going to be more male poisoners than female.”

While it’s not a perfect science, Johnston says research has indicated trends in what kind of people poisoners tend to be. “They tend to be less confrontational, they tend to express their anger more indirectly, they tend to be kind of sneakier,” she says.

They are also unlikely to be career criminals; Patterson had a clean record.

Poisoners are planners by necessity, but some can derive a sense of pleasure or interest in the planning process.

“What situation can you imagine where you don’t have to plan poisoning somebody?” Johnston says. “You have to get the poison. You have to administer it, even if you have it in your house.”

Lorraine Moss, Erin Patterson and Lana Clayton.Credit: Monique Westermann/AP

Patterson fits the bill as a fastidious planner. Evidence presented during the 11-week murder trial suggested a high level of planning. A year before the fatal lunch, she researched death cap mushroom sightings in the area and practised hiding dried mushrooms in her children’s food.

Johnston says: “How angry they are can determine how much pleasure they get out of the planning process, because when you think about poisoning, especially [in instances where the victim is poisoned over a period of time] there’s a sadistic part of that as well.”

The elaborate planning is likely to cost Patterson a lenient sentence as the judge deliberates the length of her imprisonment.

When choosing a poison to administer, the murderer often turns to something that can be acquired without difficulty.

Johnston points to a case, also in the US, where a veterinarian murdered her husband with animal tranquiliser. There have been a few cases in which doctors have used colchicine, a medicine used to treat gout, to murder their victims.

Patterson, a former council worker who was a homemaker at the time of her crimes, joins a long list of women who have used food to administer their poison. Johnston says this again comes back to accessibility – the women’s role in the home, especially historically, was to cook. “If you wanted to get rid of somebody, then you had some opportunity as a caretaker or as a food provider,” she says.

Bendigo woman Lorraine Moss slowly poisoned her husband, Johnny Moss, to death by covertly feeding him large quantities of arsenic and lead over a number of years. After years of symptoms that baffled doctors, he died a slow and excruciating death. Moss borrowed books about poison and was seen to be highly calculated; the homicide detective who charged her said it was a case of “cold-blooded torture” – although she was always polite to the police.

Why Erin Patterson captured the world’s attention

Patterson is not the only person in Australia accused at present of crimes involving poison, but few cases have captured the public’s attention quite like Patterson’s fatal beef Wellington lunch. Journalists, podcasters and film crews descended on the little town of Leongatha in the aftermath of the deaths; during the trial in nearby Morwell, true crime buffs queued in the rain outside the court for hours to get a seat inside. There were daily news bulletins, live blogs and YouTube channels.

Criminologist Kathryn Whiteley says the frenzied interest in the mushroom case is threefold. The first is the theatrical nature of the crime, almost Shakespearean in its spectacle. The second is the number of victims – mass killers are rare. And rarer still are female killers.

‘Did she – or does she – feel sincere remorse, bewilderment with the knowledge of her family dying from the meal she provided, or a callous sense of relief, if her agenda was revenge?’

Criminologist Kathryn Whiteley

Men are overwhelmingly responsible for Australia’s homicides. Data from the Australian Institute of Criminology between July 2023 and June 2024 found women committed just 13 per cent of homicides during that time. Whiteley says this statistic is consistent across the Western world, where women account for about 10 per cent of murders.

“Generally speaking, we as a society conceptualise a woman’s traditional values with nurturer, carer, the gentler sex,” Whiteley says. “The notion that a woman can give life to a human being and then violently take another challenges societal norms of womanhood. It shocks our societal psyche.”

But why do women kill less than men? This is a challenging question to answer, Whiteley says. Research suggests biological differences can play a role, as well as gendered societal norms.

“Testosterone in males is equated to higher impulsivity and low frustration tolerance. It’s thought with women’s progesterone, there exists more placidity and compliance,” Whiteley says.

“When a male’s goals are blocked, they may become frustrated and angry, which can lead to violent behaviour. Women, on the other hand, have traditionally been taught to talk through their frustration and anger, or as many women do, internalise it. Women’s aggression is far more relational or indirect, rarely physical.”

Erin Patterson and Simon Patterson.Credit: Jason South

Whiteley, whose research focuses on the portrayals of women who kill, spent months interviewing seven women convicted of murder at Dame Phyllis Frost prison – the prison in which Patterson will serve her sentence. She says the interest is typical of any case when the offender is female.

“Women receive far more media coverage, no matter the platform … Women are relegated by media with common, often more damning adjectives.”

One of those damning assessments of Patterson has been her “crocodile tears”. The accused often wept during her eight-day testimony, but reporters in the courtroom observed no genuine tears forming and the tissues she pressed to her face were conspicuously dry.

The scene echoed Patterson’s first public interview in August 2023, when the 50-year-old pleaded her innocence to journalists outside her Leongatha home a week after hosting the fatal lunch.

Observing Patterson’s body language in the video, Whiteley noted the way she would wipe her tears. “It appeared almost forced, with exaggerated hand gestures on and around her face; by wiping her face, her eyes, to show that she was emotionally upset, reflecting the overall personal impact this tragic event has on her now.”

This is not necessarily an indicator of guilt – Whiteley has sat across and spoken to many women convicted of murder whose eyes will well, but tears won’t fall. “Many continue to put on a ‘brave’ facade because they do not want to let their guard down, as this can appear to society as a sign of personal weakness,” she says.

When Patterson was first confronted by reporters on that Monday in August, Whiteley observed the mother of two appearing slightly emotional but willing to talk about her relationships with her lunch guests.

“Within minutes after being further provoked to answer questions by journalists who wanted more specific information about the crime itself, she appears traumatised, more emotionally unsettled, and keeps repeating, referring back to a similar, themed message.

“Some may suggest in these later instances, where Erin continues to provide almost the same narrative response to the journalists, there is an emotional disconnect between the question being pursued and what she answers – almost like a rehearsal.”

Interestingly to Whiteley: “She doesn’t appear to sincerely, genuinely apologise for having cooked the lunch, which made them ill.”

For Johnston, her interest in the case was piqued not by the gender of the offender, but rather the scale of the crime.

“The thing that struck me the most is why would you kill all of these people?” she says. “The extreme nature of that, I do think she really did end up, in her mind, blaming this whole family for the deterioration of her marriage, and felt like they mistreated her in some way. And that became an obsession or focus for her.”

This was a narrative the prosecution put forward during the case. The jury heard that a Facebook account linked to Erin Patterson sent messages to a chat group saying her estranged husband was a “deadbeat” father and his parents were “a lost cause”.

The other puzzling detail for Johnston was a seeming lack of financial motivation, something she says is often the motivator in similar cases. “I know there was something about money [but it wasn’t central to the case] … for her, I could see money becoming somewhat symbolic, whether she needed it or not.”

Whiteley’s interest has turned to Patterson’s mental state on July 29, 2023: “One does consider what was Erin feeling emotionally, as she prepared the lunch on that day and served the food to her family members.

“Did she – or does she – feel sincere remorse, bewilderment with the knowledge of her family dying from the meal she provided, or a callous sense of relief, if her agenda was revenge?”

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