Law enforcement officials nationwide are demanding the creation of a “kill switch” that would render smartphones inoperable after they are stolen, New York’s top prosecutor said Thursday in a clear warning to the world’s smartphone manufacturers.

Citing statistics showing that 1 in 3 robberies nationwide involve the theft of a mobile phone, New York Attorney General Eric Schneiderman announced the formation of a coalition of law enforcement agencies devoted to stamping out what he called an “epidemic” of smartphone robberies.

“All too often, these robberies turn violent,” said Schneiderman, who was joined at a news conference by San Francisco District Attorney George Gascon. “There are assaults. There are murders.”

The coalition, which is called the Secure Our Smartphones Initiative and includes prosecutors, police, political officials and consumer advocates from more than a dozen states, will pressure smartphone companies and their shareholders to help dry up the secondary market in stolen phones.

The announcement came on the same day Gascon and Schneiderman were scheduled to co-host a “Smartphone Summit” with representatives from major smartphone makers Apple Inc., Samsung Electronics Co., Google Inc. and Microsoft Corp.

“We’re prepared to deepen our inquiry if that is appropriate,” Schneiderman said, though he would not elaborate on how far his office might go to ensure that manufacturers comply with the coalition’s demands.

He likened the functionality of a “kill switch” to the ability for consumers to cancel a stolen credit card.

The general public should not be forced to pay more for smartphones that have a “kill switch,” Schneiderman said.

Apple said at a developers’ conference this week that such a feature would be part of its iOS7 software to be released in the fall. Gascon and Schneiderman said in a statement they were appreciative of the gesture but would reserve judgment until they could “understand its actual functionality.”

“Apple has been very vague as to what the system will do,” Gascon said at the news conference. “We’ve been led to believe that it is not a ‘kill switch.’ “

Gascon was particularly critical of Apple, saying that he had met with the company in January but was rebuffed by executives.

“The industry has a moral and social obligation to fix this problem,” Gascon said.

To drive home their point about the danger of violent smartphone thefts, authorities introduced relatives of 23-year-old Megan Boken, who was shot and killed in St. Louis in 2012 by an assailant who was trying to steal her iPhone.

Boken was chatting with her mother on the phone at the time, said her father, Paul Boken.

“All of a sudden, the phone went blank,” he told reporters. “Megan never picked the phone up again.”

In New York, police have coined the term “Apple-picking” to describe thefts of the popular iPhone and other mobile products, like iPads. Phone thefts make up 40 percent of all robberies in New York City, authorities say.

Authorities are pushing for the industry to move ahead quickly with this new security-focused technology. By early next year, all smartphones should be equipped with the new protective software, Schneiderman said.