The arrest of al-Qaeda leader Mamdouh Mahmud Salim (a.k.a. Abu Hajer) points US and German investigators to Mohammed Haydar Zammar, a member of the al-Qaeda cell in Hamburg, Germany, with a few of the future 9/11 hijackers. Salim is arrested on September 16, 1998, in Munich, Germany (see September 16, 1998). He is believed to be al-Qaeda’s financial chief, and is one of al-Qaeda’s founding members (see August 11-20, 1988). After Salim’s arrest, both German and US intelligence investigate his contacts in Germany and discover a link to Zammar. Zammar is already being investigated and monitored by the Office for the Protection of the Constitution (BfV), Germany’s domestic intelligence service (see March 1997-Early 2000). [Der Spiegel (Hamburg), 12/12/2005] Presumably, the link between Zammar and Salim should increase the urgency of the German investigation. It is unknown when US intelligence begins monitoring Zammar, but the US will discover important links between Zammar and al-Qaeda in the summer of 1999 (see Summer 1999). US and German investigators also discover a link between Salim and Mamoun Darkazanli, a Hamburg associate of Zammar’s, and they monitor him as well (see Late 1998).