A prompt warrantless arrest by a citizen for a misdemeanor occurring in her presence is lawful. Appellant made so many harassing 911 phone calls over a period of time that the dispatchers came to recognize his voice. One day, he made approximately 20 to 25 calls to dispatcher, Ms. T., who finally sent a police officer to appellant’s location and requested a citizen’s arrest. Appellant appealed the denial of his 1538.5 motion, contending the citizen’s arrest was not lawful as the police officer did not have authority to perform a citizen’s arrest for an offense not committed in his presence. The appellate court disagreed. Under Penal Code section 837, a private person may arrest another for a public offense committed in his presence. “Presence” is liberally construed and does not require physical proximity, but the crime must be apparent to the person’s senses, including the sense of hearing. Thus, a public offense may be committed in a person’s presence if his auditory perception is effected by an electronic device, such as a telephone, as was the case here with the harassing calls to the dispatcher. Additionally, presence relates only to the commission of the offense, and not to the arrest, which may be delegated to a police officer. The arrest must be made "promptly" after the commission of the offense and cannot be justified after the occasion has passed. Here, the promptness requirement was met since Ms. T. dispatched the officer and promptly executed the citizen’s arrest form immediately after the harassing phone call.