In the 1980’s, DNA analysis were found and had became a great advance crime-solving tool for investigators. DNA analysis were created to be used in crime cases and it can help clear suspects and identify criminals. Also, television shows like “CSI” had helped increase the public’s awareness of DNA analysis that can be a great advancement for investigating crimes. To get more identification and comparison, the CSI will conduct the analysis of the body fluid also including DNA analysis that are blood stains, semen, hair and saliva. In all, DNA technology is progressively critical to assure authority and fairness in the criminal justice system. Most of the cells that make up a human body are diploid cells that has a same exact DNA, except for haploid gametes (egg and sperm) and red blood cells. The biological material that were used in DNA profiling includes blood, semen, saliva, urine, feces, hair, teeth, bone, tissue, and cells. Though some are more useful than others, the areas that used biological evidence in DNA and genetic analysis varies includes blood typing, gender determination, DNA profiling and forensic DNA phenotype. The DNA-testing technology had become a powerful criminal justice tool. It is very useful for identifying suspects for a crime investigation. An example of a crime that was solved provided by the DNA evidence is in 2001, when serial killer Gary Leon Ridgway, also known as the “Green River Killer” was born on February 18, 1949, he held a job painting trucks for 30 years and was married 3 times. Ridgway’s killings began in 1982. He brought many of the young delinquents and prostitutes home, strangled and choke them to death, then he left them in the woods.He eludes the law until 2001, when King County sheriff Dave Reichert, also is the first officer assigned to the case in 1982, had reconsidered and decided to have a meet up to re-examine the evidence using a newly developed DNA-testing technology. Despite a large law administration task force and a $15 million investigation, the DNA evidence has provided a major breakthrough in the series of crimes that have been unsolved for many years. In 2013, Ridgway had claimed that he had murdered 75-80 women. But DNA evidence also can be unreliable for the potential assault of the individual who was analyzed. The DNA of the person reveals so much information, some of them had become too sensitive that had to be carefully guarded. Another disadvantages of DNA evidence is that it can be fallible. Since we leave traces of our DNA everywhere like dead skin cells, stray split, or strands of hair. It can be difficult for investigators to tell the difference about the DNA that belongs to the criminal and the DNA that had randomly find its way to the crime scene. Sometimes DNA analysis can lead to the practice of eugenics. It can allow only desirable genetic characteristics to be passed on to a generation of children. But this type of action can also be ethical because it can be considered interfering with nature and may run counter to some religious beliefs.DNA analysis is now become an important step at a crime scene investigation. The DNA analysts will process all of the evidence that were found at the crime scene after the CSI had makes their way through the scene, collecting all the potential evidence. As a matter of policy, DNA evidence can only be used in violent crimes, including homicide and sexual assault. But after all, DNA analysis had become a major criminal justice tool that had helped so much in criminal cases.