A certain federation's former chairman was arrested on suspicion of breach of trust.
Literal
Certain federation former-chairman [subject-が] breach-of-trust [possessive-の] suspicion [with-で] arrested-[passive-されました].
某 'a certain, unnamed' — used in news when not identifying the organization. 背任の容疑で 'on suspicion of breach of trust' — standard legal/news phrasing. 逮捕されました is passive — 'was arrested.' Formal news-report register.