no support for a city that ignores the strong evidence that should be acted on. breaking overnight. new information in a san francisco shooting. a source with knowledge of the investigation telling cnn the gun used by the suspect belonged to a federal agent. this news coming as the suspect who has admitted in tv interviews to shooting kate steinle pleaded not guilty to murder. for the latest let s go to sara snidner in san francisco. reporter: a strange twist to this case. a source with knowledge to the investigation told us indeed the gun that was used in this trace actually traced back to a federal agent. now, we don t know which one and we don t know how that all came about, but we understand the gun was recovered in this case. this is happening on the same day that the suspect juan francisco lopez sanchez was in court. he was asked whether or not he was guilty or not guilty of the crime of murder in the kate steinle case and he said, in