The Spanish police arrested the popular hacker as a result of an investigation on an attack against the Catalan police union, the Sindicat de Mossos, that occurred on May 2016. A few hours after the arrest, someone using Phineas Fishers email address sent the following message: I think the Mossos just arrested some people that retweeted the link to their personal info, said Fisher in an email shared by a source of Motherboard who asked to remain anonymous.”]
Source: https://securityaffairs.co/wordpress/55885/hacking/phineas-fisher-alleged-arrest.html