**EMBARGO: No electronic distribution, Web posting or street sales before SATURDAY 3:02 a.m. ET May 19, 2018. No exceptions for any reasons. EMBARGO set by source.** Phones that have been under investigation, at the Dakota County Sheriff’s Office in Hastings, Minn., May 15, 2018. As digital tools that gather cellphone data for tracking children, friends or lost phones have multiplied in recent years, so have the options for people who abuse the technology to track others without consent. (Jenn Ackerman/The New York Times)