MEXICO CITY — In El Salvador, the number of murders plunged by nearly half between February and March. Neighboring Honduras has also seen a falloff in killings in recent weeks, as has Colombia and the most populous state in Mexico. As nations around the world contend with a growing number of fatalities caused by the coronavirus, some are simultaneously experiencing an unanticipated — and welcome — decline in a different form of death: murder. Governments around the world have imposed travel restrictions, curfews and quarantines to help control the spread of the virus, and by doing so they have also inadvertently lowered criminality and violence — for the moment, at least. CORONAVIRUS UPDATESTurkey abruptly orders a lockdown, and China says it will delay the export of crucial medical supplies. The trend has been particularly notable in Latin America, the region with the highest homicide rates in the world outside of war. “It’s taking people off the streets,” Alejandro Hope, a securi...