The investigation is based upon leaked emails from Ždanoka herself with persons identified convincingly by invetigators as members of the Russian security and spying services. It also includes references to some of Ždanoka's activities previously reported by LSM such as her notorious visit to Syria.
"Leaked emails between Ždanoka and her two known Russian case officers include explicit, detailed reports from Ždanoka to her handlers describing her work as a European legislator, particularly as those official duties relate to fostering pro-Kremlin sentiment in her native Baltic region. Other correspondence involves arranging physical meetings in Moscow or Brussels between Ždanoka and her Russian handler, along with requests for funding from Russian sources to underwrite her political activities in Latvia and the European Parliament," says the investigation, which can be read in full here: https://theins.press/en/politics/268694.