The top prosecutors in San Francisco and New York say they are bringing in state and federal security experts to test the newest anti-theft features designed to thwart the surge of stolen smartphones across the US.
San Francisco District Attorney George Gascon and New York Attorney General Eric Schneiderman have announced the security experts will be in San Francisco to test Apple's iPhone 5 with its activation lock and Samsung's Galaxy S4 with Lojack for Android.
Mr Gascon said the experts will treat the phones as if they were stolen and try circumventing its anti-theft features to draw their own conclusions on its effectiveness.
"We are not going to take them at their word," the prosecutors said in a joint statement. "Today we will assess the solutions they are proposing and see if they stand up to the tactics commonly employed by thieves."
Last month, Mr Gascon and Mr Schneiderman met in New York City with representatives from Apple, Samsung, Google and Microsoft as part of their Secure Our Smartphones initiative urging them to create a "kill switch" to render stolen smartphones inoperable.
The prosecutors said they "asked the companies to commit to develop effective solutions to this national crime wave and install them on all new products within one year".
Almost one in three robberies nationwide involves the theft of a mobile phone, according to the Federal Communications Commission, which is coordinating the formation this autumn of a US-wide database system to track mobile phones reported stolen.
"Together, we are working to ensure that the industry embed persistent technology that is effective, ubiquitous and free to consumers in every smartphone introduced to the market by next year," the prosecutors said.
Lost and stolen cellphones cost consumers more than 30 billion dollars last year, according to a study cited by Mr Schneiderman in June. 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 comprise 40% of all robberies in New York City, authorities said. In San Francisco, half the robberies were phone-related last year.