You can also look at real estate websites not all agents put signs on vacant properties.
Probably the easiest way is to contact your local Police Department using the non emergency number or the number for the officer in charge of the station, and explain your concern. Many area departments have house check systems and can provide information on the status of many properties. I would also suggest speaking with the Police as they might want to check the house to make sure none is injured inside the home.
Hope that helps!! Good luck!