Officer Cyril Rombach of the Burbank Police Department, an experienced and well-trained narcotics officer, applied for a warrant to search several residences and automobiles for cocaine, methaqualone, and other narcotics. Rombach supported his application with information given to another police officer by a confidential informant of unproven reliability. He also based the warrant application on his own observations made during an extensive investigation: known drug offenders visiting the residences and leaving with small packages, as well as a suspicious trip to Miami by two of the suspects. A State superior court judge issued a search warrant to Rombach based on this information. Rombach’s searches netted large quantities of drugs and other evidence, which produced indictments of several suspects on charges of conspiracy to possess and distribute cocaine. The defendants moved to suppress the evidence on the grounds that the search warrant was defective in that Rombach had failed to establish the informant’s credibility and that the information provided by the informant about the suspect’s criminal activity was fatally stale. The district court declared that the search lacked probable cause, that the warrant was invalid, and that the obtained evidence must be excluded from the prosecution’s case under the Fourth Amendment’s exclusionary rule. The Court of Appeals for the Ninth Circuit affirmed. Should the evidence be excluded? Why?