One law enforcement official in New Jersey, who spoke on the condition of anonymity, likened the trend in Newark to a “ride-share program” for criminals.

The rise in carjackings comes at a time when Newark is experiencing high rates of other violent crimes. With a population of less than 300,000 people, Newark has already seen at least 100 murders this year, and the feeling of lawlessness among some residents is palpable.

Law enforcement officials and criminologists also said that Newark’s proximity to major ports — one in Newark and another in nearby Elizabeth — has contributed to the increase, giving thieves the ability to move stolen cars quickly to overseas markets. Indeed, in some cases, carjackers are simply looking for a car they can use to commit another crime and then dump. Some are targets of opportunity; others are orchestrated by organized car-theft rings that send vehicles for resale in Africa, law enforcement officials said.

This year, the victims included a Newark politician, an off-duty police officer and a police sergeant. The trend is so acute that it has inspired a Twitter account, @NewarkCarjacked, which alerts followers to most new cases.

Paul Telekian, the owner of Empire Auto Body in the city’s Ironbound section, said some of his clients refuse to drive to his shop. So he arranges to meet them in West Orange, and drives the cars in himself.

“The insecurity is deep now,” he said.

On the same day the lawyer, Dustin J. Friedland, was killed, three men wearing ski masks and brandishing a handgun carjacked a man in South Orange, another Newark suburb, fleeing with his Land Rover, according to the South Orange police. Although some law enforcement officials speculated that the two crimes could be related, there was no evidence connecting the carjackings, the police said.

Efforts to address the problem have yet to yield significant results. Responding to the spike in carjackings, New Jersey in 2010 created four regional task forces composed of municipal, county, state and federal law enforcement personnel, to assist with investigations. Those task forces have mainly dealt with investigating carjackings, rather than preventing them, officials said.