In the 1990’s DNA testing started to become popular particularly in the area of Law Enforcement. Old pieces of evidence to include hair, blood and semen which were once not able to provide evidence now were able to be processed and evidence and a DNA profile could be extracted from the materials. Thanks to DNA many unsolved cased were able to be solved and many suspects of crimes were finally able to be charged. DNA has also helped the innocent from wrongful incarceration. DNA evidence is becoming mandatory in states in terms of death row inmates and proving that the right person is behind bars. In 2000, Illinois Governor George Ryan announced his plan to suspend all of the states executions indefinitely. Governor Ryan’s made this landmark statement after DNA testing showed that 13 Illinois death-row prisoners could not have committed the capital crimes of which they were convicted.

DNA is not just putting people in prison; it is also ensuring that those in prison should be there. DNA is being used to confirm the conviction and ensure that the right person is serving time for the crime. In what is bring described as the first effort of it’s kind San Diego prosecutors are reviewing hundreds of old cases to see if longtime prison inmates can be cleared by DNA evidence. If evidence is found, the San Diego County District Attorney’s office will have it tested for free if an inmate agrees. Not only does this get innoscent people out of prison it also helps to build out the national DNA database. Part of the DNA testing of inmates is that the inmate’s DNA will end up in a national database where it may be used to solve other cases which have gone unsolved. San Diego Country Prosecutors are looking at a total of 560 criminal cases.

Since DNA has been introduced thousands of suspects and prison inmates have been cleared and released as a result of DNA evidence showing they could not have been responsible for the crime. A popular case that outlined this is the Larry Youngblood case. Larry Youngblood was convicted in 1985 of child molestation, sexual assault, and kidnapping. He was sentenced to ten years and six months in prison. In October 1983, a ten year old boy was abducted from a carnival in Pima County, Arizona, and molested and sodomized repeatedly for over an hour by a middle aged man. The victim was taken to a hospital, where the staff collected semen samples from his rectum as well as the clothing he was wearing at the time of the assault.

Based on the boy's description of the assailant as a man with one disfigured eye, Youngblood was charged with the crime. He maintained his innocence at trial, but the jury convicted him, based largely on the eyewitness identification of the victim. No serological tests were conducted before trial, as the police improperly stored the evidence and it had degraded. Expert witnesses at trial stated that, had the evidence been stored correctly, test results might have demonstrated conclusively Youngblood's innocence.

Larry Youngblood appealed his conviction, claiming the destruction of potentially exculpatory evidence violated his due process rights, and the Arizona Court of Appeals set aside his conviction. He was released from prison, three years into his sentence, but in 1988, the Supreme Court reversed the lower court's ruling, and his conviction was reinstated (Arizona v. Youngblood, 488 U.S. 51). Youngblood remained free as the case made its way through the Arizona appellate court system a second time, but returned to prison in 1993, when the Arizona Supreme Court reinstated his conviction.

In 1998, Youngblood was released on parole, but was sent back to prison in 1999 for failing to register his new address, as required by Arizona sex offender laws. In 2000, upon request from his attorneys, the police department tested the degraded evidence using new, sophisticated DNA technology. Those results exonerated Youngblood, and he was released from prison in August 2000. The district attorney's office dismissed the charges against Larry Youngblood that year.

In 1990, the FBI established its database containing genetic profiles from unsolved crimes and from convicted offenders. In October 1998, the FBI's National DNA Index System (NDIS) became operational. The database is the (CODIS) Combined DNA Index System, a computerized forensic database of DNA “profiles" of offenders convicted of serious crimes (such as rape, other sexual assaults, murder, and certain crimes against children), as well as DNA profiles from unknown offenders. CODIS generates investigative leads in crimes where biological evidence is recovered from the crime scene using two indexes: the forensic and offender indexes. By 1998, every state had enacted legislation establishing a CODIS database and requiring that DNA from offenders convicted of certain serious crimes be entered into the system.

Today, the CODIS database contains about 400,000 DNA profiles, and the number is growing. CODIS is implemented as a circulated database with three tiers - local, state, and national. NDIS is the highest level in the CODIS hierarchy, and enables the laboratories participating in the CODIS Program to exchange and compare DNA profiles on a national level. All DNA profiles originate at the local level (LDIS), then flow to the state (SDIS) and national levels. SDIS allows laboratories within states to exchange DNA profiles. The tiered approach allows state and local agencies to operate their databases according to their specific legislative or legal requirements. It is being enhanced daily through the work of federal, state, and local law enforcement agencies who take DNA samples from biological evidence gathered at crime scenes and from offenders themselves. The computerized CODIS system can rapidly identify a perpetrator when it finds a match between an evidence sample and a stored profile. As of 2003, the database had profiled approxminaly 66,000 unsolved cases and more than 1.5 million convicted offenders.

Matches made among profiles in the Forensic Index can link crime scenes together; and even identifying serial offenders. Based on a match, police in multiple jurisdictions can coordinate their respective investigations, and share the leads they developed independently. Matches made between the Forensic and Offender indexes provide investigators with the identity of the perpetrator(s). After CODIS identifies a potential match, qualified DNA analysts in the laboratories contact each other to validate or refute the match.

Everyone benefits from having a national DNA database and DNA information has helped many victims, families and people who were either the victim of a crime or victimized by the criminal justice system and wrongfully convicted. The DNA database provides a very large resource which provides a conclusive way to show whether or not someone had anything to do with a crime. The database has also closed thousands of cases which would have otherwise gone unsolved indefinitely.