Pandora and other app makers received subpoenas related to a criminal federal investigation in which prosecutors are looking into claims that smartphone apps violate users’ privacy by illegally collecting and transmitting info.

The Wall Street Journal reports the feds are examining whether app developers described their intentions with the information and explained why they needed it. The investigators contend the collection of information, including a user’s location or info that identifies the phone, violates a federal law against computer fraud.

According to the WSJ, the feds are on to something because it tested 101 apps and found that 56 transmitted information without notifying the user.

Pandora says it’s not a specific target of the investigation and believes other companies in the industry received subpoenas.

Mobile-App Makers Face U.S. Privacy Investigation [The Wall Street Journal via Engadget]

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