Riley v. City of Montgomery, Ala., 104 F.3d 1247 (11th Cir. 1997) (citing magistrate judge's report, which concluded that a lead "[police detective] routinely falsified records and may well have lied about the existence of a confidential informant").
Morgan Cloud, "The Dirty Little Secret," 43 Emory L.J. 1311 (Fall 1994) (collecting examples of police perjury).
Robert Bauman, "Good Faith Breeds Bad Cops," Reason (May '95) ("A 1988 investigation of the Boston police Drug Control Unit revealed that its members routinely fabricated the existence of informants and lied to obtain warrants from judges.") [I can't find the report online, but a search of Lexis-Nexus of periodicals from 1988 should turn up some reliable citations. The investigation was conducted after a police shooting.]
Curt Brown, "Attorneys Pore over Past Cases," South Coast Daily (Aug. 17, 2001). A judge found that a police detective made false statements in an affidavit. Because of the police officer's perjury, the judge demanded that the detective produce a confidential informant the detective had allegedly relied upon in previous warrant applications. Rather than produce the informant, prosecutors dismissed a pending criminal case.
Maro Robbins, "Undercover cop put on night shift," San Antonio Express-News (Feb. 18, 2001) ("Federal prosecutors have dismissed two cocaine cases and scaled back a third because an undercover police officer lied about his information source in a sworn statement requesting search warrants.") [The SA Express-News requires a payment of $2.95 for the full article, though a summary of the article is available here.]