UPDATE: Maine State Police say Geraldo Mbacu has been found safely.Maine State Police have issued a Silver Alert for a missing 12-year-old boy from Portland.Twelve-year-old Geraldo Mbacu was last seen around 10 a.m. Monday at his home on Cumberland Street. Police say he has only been in the city for four days and is not familiar with the area. He may also be experiencing some mental health issues.Mbacu is 4 feet and 10 inches with brown hair and brown eyes. He may be wearing gray and blue shorts.Anyone with information is asked to call 911 or Portland Police at 207-874-8479.