The US Secret Service has raided the home of an artist who collected images from webcams in a New York Apple store.
Kyle McDonald is said to have installed software that photographed people looking at laptops then uploaded the pictures to a website.
Mr McDonald said he had obtained permission from a security guard to take photos inside the store.
Apple declined to comment. However, the Secret Service confirmed that its electronic crime division was involved.
A spokesperson told the BBC that the investigation was taking place under US Code Title 18 /1030 which relates to "Fraud and related activity in connection with computers."
Offences covered by the legislation carry a maximum penalty of 20 years in prison.
Writing on Twitter, Mr McDonald said: "@secretservice just stopped by to investigate [web address removed] and took my laptop. Please assume they're reading any e-mails you send me."
No arrests had been made in the case as of 8 July.
Kyle McDonald's images were uploaded to a page on the blogging site Tumblr.
In the description of People Staring at Computers, the project is described as: "A photographic intervention. Custom app installed around NYC, taking a picture every minute and uploading it if a face is found in the image.
"Exhibited on site with a remotely triggered app that displayed the photos full screen on every available computer."
The site features a video and series of photographs, apparently showing shoppers trying-out computers.
Comments on the individuals by visitors to the site are also attached to the images.
Mr McDonald, writing on Twitter, said that he had been advised not to comment on the case by the online freedom group the Electronic Frontier Foundation.