Bielefeld (dpa) - Large-scale operation of the police in Detmold and the surrounding area: A helicopter and dogs are looking for in the 70 000-inhabitant city in the district of Lippe a 15-year-old. The terrible suspicion: She is said to have killed her little half-brother. According to the investigators, the three-year-old was fatally injured with a knife. A police spokeswoman told the German press agency that the boy had been found by a relative. From the half sister first was missing any trace. The Procuratorate and Criminal Investigation Department initiated a publicity search for the teenager.