Complex sentence: Doshuyev had been detained and amnestied by federal forces in early 2000; notably, Moscow very unsuccessfully tried to use him as a witness in their 2003 attempt to have Zakayev extradited from his exile in London.
Split into simpler sentences: Doshuyev had been detained and amnestied by federal forces in early 2000. Notably, Moscow very unsuccessfully tried to use him as a witness in their 2003 attempt to have Zakayev extradited from his exile in London.