(Telecompaper) New York state attorney general Eric Schneiderman has written to Apple, Google, Microsoft and Samsung asking the companies what they are doing to fight mobile device thefts and to deter a black market for the products, Bloomberg reports. Schneiderman sees the thriving black market for stolen handsets as an indication that manufacturers have not produced technology to make stolen phones inoperable. He wrote that he would be particularly concerned if the phonemakers benefited from increased sales of replacement handsets. According to New York City police, there was a 40 percent increase in the theft of Apple devices between January and September 2012, compared to the same period a year earlier.