A former cybersecurity executive at Twitter has blown the whistle on his observations of systemic data security lapses at the company, undercounting of fake accounts, and how the social media platform could be manipulated by foreign intelligence services.

Peiter “Mudge” Zatko, Twitter’s former head of security, sent a 200-page disclosure to Congress and several regulatory agencies in July outlying the alleged problems in detail, according to reports Tuesday by CNN and theWashington Post.

Zatko said he was fired by Twitter in January after he shared his concerns internally with management, including Chief Executive Parag Agrawal, who was once the company’s chief technology officer.