Back during the summer, we wrote about how the FBI was increasingly using malware to spy on people (though they apparently tried to avoid using it with technically savvy people to avoid having its capabilities „discovered“). However, the Washington Post has more details on how the FBI uses malware in trying to track down someone, based on court documents — though it also notes that at least some courts have balked at such techniques, pointing out that they go way too far and probably violate the 4th Amendment.