The FBI has an elite hacker team that creates customized malware to identify or monitor high-value suspects who are adept at covering their tracks online, according to a published report.

The growing sophistication of the spyware—which has the capability to remotely activate video cameras and report users’ geographic locations—is pushing the boundaries of constitutional limits on searches and seizures, The Washington Post reported in an article published Friday. Critics compare it to a physical search that indiscriminately seizes the entire contents of a home, rather than just those items linked to a suspected crime. Former US officials said the FBI uses the technique sparingly, in part to prevent it from being widely known.

The 2,000-word article recounts an FBI hunt for “Mo,” a man who made a series of threats by e-mail, video chat, and an Internet voice service to detonate bombs at universities, airports, and hotels across a wide swath of the US last year. After tracing phone numbers and checking IP addresses used to access accounts, investigators were no closer to knowing who the man was or even where in the world he was located. Then, officials tried something new.