Complex sentence: Anwar al-Awlaki was an American cleric who became linked to the 9/11 hijackers from evidence obtained by German law enforcement during a search of an apartment owned by Ramzi bin al-Shibh, widely regarded as a key facilitator of the 9/11 attacks.
Split into simpler sentences: Anwar al-Awlaki was an American cleric who became linked to the 9/11 hijackers from evidence obtained by German law enforcement. This evidence was obtained during a search of an apartment owned by Ramzi bin al-Shibh, widely regarded as a key facilitator of the 9/11 attacks.