- Authorities are trying to nail down a motive behind the Monterey Park Lunar New Year mass shooting.
- The shooter was 72 years old, making him one of the oldest mass shooters in US history.
The gunman behind the Monterey Park, California, mass shooting Saturday was one of the oldest in US history, shattering an American recurrence of younger and middle-aged mass shooters.
The shooter, who was 72 years old, doesn't fit into the brackets of age ranges typically associated with mass shooters and could be tied to rising suicides in elder communities, a gun violence expert told Insider.
"People this old don't commit many crimes, generally," Dr. Jillian Peterson, a researcher at Hamline University who runs the Violence Project and has created a database of every US mass shooting since 1966, told Insider.
Often, it's teenage shooters who commit shootings at schools and young men between the ages of 18 to 25 who shoot at restaurants, stores, or universities, Peterson said.
"That maps onto who commits a lot of violence, your brain's not fully matured," she said, referring to younger people. Medical studies show that the prefrontal cortexes in the brains of men — who make up the majority of mass shooters in the US — do not fully mature until they reach 25 years old.
Peterson suggested that younger people are more prone to lashing out through violence and feeling no sense of place in their lives. There is also less of a risk assessment for younger perpetrators, and they are more prone to post and be inspired by manifestos, Peterson added.
"People will release manifestos, or diaries, or videos or something to help the world understand," why they committed a mass shooting, Peterson told Insider. "A lot of times, these are a way to get your grievance out into the world to make people see it and force people to watch."
"We see another cluster in the mid-40s. A lot of those tend to be workplace shooters, so perpetrators get fired or suspended from their job and then go back and kill everyone and themselves," she said.
However, the research on older shooters is more limited. Days after the Monterey Park shooting, a 67-year-old man was taken into custody as the suspect for a shooting in Half Moon Bay, California, where 7 people including Chinese farm workers were shot and killed.
The shooter in Monterey Park who killed 11 and injured 9 during the city's Lunar New Year celebration was only the second mass shooter over 70 identified by The Violence Project, which tracks 200 different pieces of each shooter's life history information to better understand the perpetrators' motives. Stephen Paddock, the Las Vegas shooter who killed 60 people at a concert from the balcony of the Mandalay Bay Hotel, was 64 years old.
Data points around suicide could be useful in helping to understand why an older individual may commit a mass shooting, according to Peterson. Men over 75 years of age committed the highest rate of suicide among any demographic by sex and age in 2020, according to the CDC. Peterson said that the rise of that figure in the context of mass shootings by older gunmen was concerning. The Monterey Park gunman shot himself before he was apprehended by police.
Sometimes, mass shootings can be viewed as a "form of suicide or a form of death of despair because there's never a plan to escape, it's always designed to be a final act," Peterson said.
As investigators glean information about the shooting — the fifth US mass shooting in January — details are still few and far in between. Monterey Park mayor Henry Lo told Insider on Monday that the shooter formerly frequented the dance club where he carried out the shooting.
"He didn't leave behind much to help explain why he did it," Peterson said. But "we tend to see this pretty consistent pathway amongst shooters where it's early childhood trauma or family violence escalating over time to a very clear crisis point."