In crime investigation, DNA fingerprinting is powerful tool in hands of biologist to detect criminal. DNA is isolated from different sources like Blood, Blood stains, Semen, Tissue, Bones, Hair in different cases of Murder, Rape, Dacoit, Individual Identification and Paternity. Most of the disputed paternity cases arise in the context of adultery or fornication, questioned legitimacy, guardianship, affiliation orders, divorce proceedings etc. In this sexual assault case, a girl aged 14, when her father raped her repeatedly, resulted to pregnancy and in spite of all the witnesses along with victim turned hostile; it was the only DNA test report that charged father after his paternity proved.