Webb is best known for his "Dark Alliance" series, which appeared in "The Mercury News" in 1996. The series examined the origins of the crack cocaine trade in Los Angeles and claimed that members of the anti-communist Contra rebels in Nicaragua had played a major role in creating the trade, using cocaine profits to finance their fight against the government in Nicaragua. It also stated that the Contras may have acted with the knowledge and protection of the Central Intelligence Agency (CIA). The series provoked outrage, particularly in the Los Angeles African-American community, and led to four major investigations of its charges.