What is the role of corroboration by the police in making a warrantless arrest?

Gates emphasized the role of corroborative investigation by the police. "Our decisions applying the totality-of-the-circumstances analysis ... have consistently recognized the value of corroboration of details of an informant's tip by independent police work. In Jones v. United States [1960] 362 U.S., at 269 [80 S.Ct. 725, 735, 4 L.Ed.2d 697], ..., we held that an affidavit relying on hearsay 'is not to be deemed insufficient on that score, so long as a substantial basis for crediting the hearsay is presented.' We went on to say that even in making a warrantless arrest an officer 'may rely upon information received through an informant, rather than upon his direct observations, so long as the informant's statement is reasonably corroborated by other matters within the officer's knowledge.' " (Id., at pp. 241-242, 103 S.Ct. at p. 2334.)

[203 Cal.App.3d 689] The purpose served by corroboration is "to establish that the information provided by the informant did not constitute a made-up story, one fabricated out of whole cloth. Corroboration of part of the information provided by the informant [gives] credibility to the remainder of the information." (People v. Medina (1985) 165 Cal.App.3d 11, 20, 211 Cal.Rptr. 216.) It is sufficient that an informant's statements are corroborated in a number of key respects, and a piecemeal approach is not required. (Ibid.)