MOSCOW—Police in Russia raided the home of the chief editor of an investigative media outlet that was recently designated as a “foreign agent,” the latest move by authorities to raise pressure on independent media before the country’s September parliamentary election. The Insider news site chief editor Roman Dobrokhotov tweeted Wednesday morning that “police are knocking” on the door of his apartment, and his wife reported the raid to the OVD-Info legal aid group before her phone became unavailable. A lawyer from another legal aid group, Pravozashchita Otkrytki, headed to Dobrokhotov’s apartment. The group said police seized cellphones, laptops, and tablets during the raid, as well as Dobrokhotov’s international passport. Sergei Yezhov, a journalist with The Insider, said that Dobrokhotov was supposed to leave Russia on Wednesday. Police also raided the home of Dobrokhotov’s parents, The Insider said. Russian opposition supporters, independent journalists, and human rights activists have faced increased government …