In-vehicle device and vehicle security system

An in-vehicle device configured to control an activation and deactivation of a monitoring device associated with a vehicle, the monitoring device configured to monitor a periphery of the vehicle and detect a suspicious person, and the in-vehicle device configured to execute a predetermined processing related to security of a user getting into the vehicle if a suspicious person is detected by one or more sensors connected to the monitoring device after the activation of the monitoring device, the in-vehicle device comprising a processor and a memory having instructions stored which, when executed by the processor, cause the processor to:

• determine if the vehicle is stopped, and as a result of determining that the vehicle is stopped, intermittently transmit a signal to at least the outside of the vehicle from a transmission antenna with which the vehicle is provided;
• receive a response signal transmitted from a legitimate portable device associated with the user, that has received the transmitted signal;
• and
• activate the monitoring device if the processor has received the response signal from the legitimate portable device, wherein the processor:
• if the suspicious person is no longer detected based on sensing information of the one or more sensors connected to the monitoring device after the predetermined processing related to security is started, measures a lapse of time from when the suspicious person is no longer detected based on the sensing information;
• if the lapse of time has passed a predetermined time period from when the suspicious person is no longer detected based on the sensing information, stops the predetermined processing related to security;
• and
• if the lapse of time has not passed the predetermined time period from when the suspicious person is no longer detected based on the sensing information, and the user performs an unlocking operation, unlocks a door of the vehicle and automatically locks the door after the door is opened and closed.