evidence: Donald Trump stoked fears of a migrant-fueled crime wave at the Conservative Political Action Conference on Saturday, describing the United States under President Biden as awash in "bloodshed, chaos, and violent crime." It was a near cut-and-paste from his CPAC speech last year, when he warned that the country was becoming a "lawless, open borders, crime-ridden, filthy, communist nightmare." [...] The first problem with Trump’s narrative is the timeline. The spike in violent crime happened on Trump’s watch, not Biden’s. In 2020, the final year of the Trump presidency, murder rose by nearly 30 percent and assault by more than 10 percent. Crime surges are almost always multifactorial, and the Covid-19 pandemic and associated economic upheaval played a major role in the historic 2020 crime surge. One cause, though, most certainly was not the Biden presidency, which had not yet begun. [...] Trump’s other baseless crime-related claim at CPAC was that newly arrived migrants are responsible for violent crime. He predicted that the current wave of migration will be "far more deadly than anyone thought." There is no evidence to support this narrative. New York City, for example, has absorbed more than 150,000 migrants since the spring of 2022. Violent crime did not increase during that time. Moreover, research conducted before the pandemic suggests that undocumented immigrants are not a major source of crime, contrary to Trump’s claim.