The national homicide “clearance rate” — that is, local police identifying and arresting killers — has slipped to 64.1 percent from more than 90 percent just 50 years ago amid shrinking budgets, higher closure standards and more crimes being committed by gangs and drug dealers who may have no local footprint and/or encourage a “no-snitch” mentality.

A homicide investigation consists of a complex array of tasks that must be performed, initially, over a short period of time, often under significant stress….prosecutors nowadays demand that police deliver “open-and-shut cases” that will lead to quick plea bargains and/or a high conviction rate for the district attorney’s office.

For instance, less than half (48.9 percent) of violent felony arrests in New York City result in a conviction and sentence, according to a report from the New York State Division of Criminal Justice Services.

As acclaimed Manhattan Institute scholar Heather Mac Donald has documented, “In Los Angeles, 95 percent of all outstanding warrants for homicide (which total 1,200 to 1,500) target illegal aliens. Up to two-thirds of all fugitive felony warrants (17,000) are for illegal aliens.”