By Michael Williams, CNN (CNN) — Two days after Alex Pretti was shot and killed by federal officers during the January immigration enforcement surge in Minneapolis, David Streever was distraught. So he fired off a three-paragraph emailed rebuke to one of the officials overseeing that operation. Five months later, that email earned Streever a knock on his door and a visit by two federal officers who issued him a stern warning and said he may have threatened Todd Lyons, then the acting director of Immigration and Customs Enforcement. That visit prompted Streever on Monday to file a lawsuit against several...