“ While a bare statement by an affiant that he believed the informant to be truthful would not, in itself, provide a factual basis for crediting the report of an unnamed informant, we conclude that the affidavit in the present case contains an ample factual basis for believing the informant which, when coupled with affiant's own knowledge of the respondent's background, afforded a basis upon which a magistrate could reasonably issue a warrant. ”

“ People do not lightly admit a crime and place critical evidence in the hands of the police in the form of their own admissions. Admissions of crime, like admissions against proprietary interests, carry their own indicia of credibility sufficient at least to support a finding of probable cause to search. That the informant may be paid or promised a 'break' does not eliminate the residual risk and opprobrium of having admitted criminal conduct. ”

“ In determining what quantum of information is necessary to support a belief that an unidentified informant's information is truthful, Jones v. United States, supra, is a suitable benchmark. The affidavit in Jones recounted the tip of an anonymous informant, who claimed to have recently purchased narcotics from the defendant at his apartment, and described the apartment in some detail. ”