This is part of an ongoing Motherboard series on the proliferation of phone cracking technology, the people behind it, and who is buying it. Follow along here.

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. Grayshift, the company that makes the device, offers two different versions: the $15,000 model offers 300 iPhone unlocks (working out to around $50 per phone), and a $30,000 version, which allows customers to unlock as many devices as they want. Both can unlock iPhones running iOS 11, Apple’s latest mobile operating system, and GrayKey works on the latest Apple hardware, including the iPhone X.

Got a tip? You can contact this reporter securely on Signal on +44 20 8133 5190, OTR chat on jfcox@jabber.ccc.de, or email joseph.cox@vice.com.

The letter also points to a recent Forbes piece, which found established mobile forensics firm Cellebrite can now unlock iOS 11 devices as well.

The lawmakers’ letter included a set of specific questions for FBI Director Wray, including whether he agrees there are solutions that can help unlock nearly every device on the market; whether the FBI has tried using third-party tools to unlock those 7,800 phones; and what is the rationale for not using such a tool to decrypt particular devices.

Motherboard has also found that regional forces, such as the Maryland and Indiana State Police have bought GrayKey; local police departments have indicated they may have purchased the device; others have received quotes for the device; the Secret Service is planning to buy six GrayKeys; and that the DEA and the FBI is looking to buy products from Grayshift.