But the gunman who murdered ten people in a rampage at a ballroom dancing centre during Chinese New Year celebrations at the weekend differed from other perpetrators of weapon-based crimes in one major respect – his age.
Huu Can Tran, 72, who opened fire at a busy event at the Star Ballroom Dance Studio in Monterey Park, near Los Angeles, on Saturday night is in a very small minority of homicide perpetrators over the age of 70. Indeed, statistics from the US for 2020 show just 61 people aged 70 to 74 are guilty of homicide of any kind – less than half a per cent of murder offenders in the country that year.
Meanwhile, in Scotland over the period between 2013 and 2022, just two people aged over 70 per million of population have been accused of homicide – a total of ten over the decade – according to Homicide in Scotland statistics.
The Monterey Park tragedy is the nation's fifth mass killing this month and the deadliest attack since May, when 21 people were killed in an elementary school in Uvalde, Texas. Last month, a boy aged six was taken into custody in Virginia after shooting his teacher following an altercation in the classroom.
Police are still trying to ascertain a motive for the attack, which saw Tran move from the first venue, to a second dance studio, Lai Lai, in the nearby town of Alhambra. There he was wrestled to the ground by a 26-year-old family member of the building’s owner, who took the gun away from him.
Five women and five men were killed in the attack, while another ten were wounded, with seven still in hospital – some in a critical condition. Tran escaped and was later found by police in his van, having apparently shot himself.
It is believed Tran had previously worked at the centre – although not for many years, with friends telling CNN he had taught ballroom dancing almost every night in the early 2000s, when he lived nearby. It is not clear whether he had been there recently.
In an interview with a US TV network, friends of the killer claimed he had been “hostile” to people at the centre during his time as a teacher. One friend said he hadn’t seen Tran in several years and was “totally shocked” when he heard about the shooting.
Although the gunman is believed to have lived close to the Monterey Park area previously, in the town of San Gabriel, he was most recently believed to be resident in a community for older people in Hemet, California, around 85 miles east of Los Angeles.
Seven years before buying the Hemet home, Tran in 2013 sold a property in San Gabriel, which he had owned for more than two decades, property records show.
Brandon Tsay, a 26-year-old coder and the operator of the Alhambra dance hall, told the New York Times he had disarmed the gunman. He said Tran was "looking at me and looking around, not hiding that he was trying to do harm".
Mr Tsay, whose grandparents opened the studio and who works there a few nights a week, said he did not recognise the gunman when the pair came face to face.
“My heart sank, I knew I was going to die,” he said, adding that he grabbed the weapon by its barrel and began wrestling for control of it.
“That moment, it was primal instinct. Something happened there. I don’t know what came over me.”
Mr Tsay said he felt like during their struggle, he was evenly matched for strength with Tran, who is almost fifty years his senior.
“We have such a tight-knit community of dancers,” he said. “It feels so terrible something like this happened, to have one of our individuals try to harm others.”
According to academics, the likelihood of committing a violent crime drops off dramatically by age. The average age of homicide offenders in most western countries is around 30, while some crimes have an even lower average age for a typical perpetrator.
This is, experts have previously claimed, a combination of crimes becoming more difficult as someone gets older, but also changes in personal circumstances – such as having children or getting a job.
A paper published by criminologists Jeffery T Ulmer and Darrell Steffensmeier, of Pennsylvania State University, argues that many hardened criminals who would choose to continue crime during their lives are more likely to have died, or become incapacitated by the time they are elderly.
"Diminishing physical capabilities as one gets older (especially beyond the 30s and 40s) make crime too dangerous or less likely to succeed," they said.
“Also, for offenders, the ‘wear and tear’ of involvement in crime and the criminal lifestyle likely take their physical toll. In addition, offenders tend to live fast and dangerously, and therefore are at greater risk of dying young or becoming physically incapacitated.”
However, the paper states that first-time offenders who commit a crime at an older age are usually triggered by a life event.
"What evidence is available on first-time older offenders suggests that situational stress and lack of alternative opportunities play a primary role,” the authors said. “The unanticipated loss of one’s job or other disruptions of social ties can push some individuals into their first law violation at any age.”