Joseph Cox, reporting for Motherboard: This week, Motherboard showed that law enforcement agencies across the country, including a part of the State Department, have bought GrayKey, a relatively cheap technology that can unlock fully up-to-date iPhones. That revelation, cryptographers and technologists said, undermined the FBI's renewed push for backdoors in consumer encryption products. Citing Motherboard's work, on Friday US lawmakers sent a letter to FBI Director Christopher Wray, doubting the FBI's narrative around 'going dark', where law enforcement officials say they are increasingly unable to obtain evidence related to crimes due to encryption. Politico was first to report the letter. "According to your testimony and public statements, the FBI encountered 7,800 devices last year that it could not access due to encryption," the letter, signed by 5 Democrat and 5 Republican n House lawmakers, reads. "However, in light of the availability of unlocking tools developed by third-parties and the OIG report's findings that the Bureau was uninterested in seeking available third-party options, these statistics appear highly questionable," it adds, referring to a recent report from the Justice Department's Office of the Inspector General. That report found the FBI barely explored its technical options for accessing the San Bernardino iPhone before trying to compel Apple to unlock the device. The lawmaker's letter points to Motherboard's report that the State Department spent around $15,000 on a GrayKey.