Local paper Phoenix New Times has covered Arpaio for over 20 years. Here’s their Twitter thread linking to all the horrible things he has done to others or that have happened under his watch. (“Horrible” actually doesn’t begin to cover it.)
Also, the judge who found Arpaio in contempt of court and sentenced him to jail was appointed under George W. Bush.
http://abcnews.go.com/US/wireStory/trumps-pardon-spares-political-ally-arpaio-49431601
[Arpaio] accused then-President Barack Obama of trying to influence the 2016 sheriff’s race by announcing in court weeks before Election Day that it was willing to prosecute Arpaio. Prosecutors never filed criminal charges. They were instead recommended by the judge who presided over the profiling case, which began in the Bush administration. The judge in the profiling case was a Bush appointee as well.