Police were able to tie a suspect to a quadruple homicide that took place in the nation’s capital in mid-May after finding DNA on pizza crust left in the home. The suspect’s DNA was already in the criminal database as a result of past crimes.
Legal Requirements to Obtaining Chicago DNA Sample
DNA is a powerful forensic tool that can link a potential suspect to a crime. Lack of a DNA match can also be used to disprove that the suspect played any part in the crime. Blood, hair, semen, skin scrapings, saliva – all are potential sources of DNA.
If police uncover DNA evidence at a crime scene, in order to get a DNA sample to compare to the evidence, the suspect must either consent to give a sample, or the police must obtain a search warrant. If the police have other evidence to tie the suspect to the crime, such as fingerprints, video surveillance footage or the victim’s identification, getting the search warrant usually isn’t that difficult.
But in some cases, DNA is the only evidence that could place the defendant at the scene of the crime, and a police officer’s hunch is generally insufficient to persuade a judge to grant a search warrant. As the Washington, D.C., case illustrates, there are other ways police can obtain a suspect’s DNA without a search warrant. Think of the scenarios that you see played out on television crime procedurals – police officers taking a cigarette butt the suspect smokes during the interrogation, the soda pop can the suspect drank from, even removing a tissue the suspect used from the trash can – all of these may be enough to give police DNA evidence that would link the suspect to the crime. And this all is obtained without the defendant’s consent or a search warrant.
The Washington, D.C. case shows how the process may sometimes work in reverse. The police may have a DNA sample obtained from the crime scene, but no known suspect. In these cases the police run the DNA sample through the Illinois DNA database, hoping for a match. The database is the result of Illinois’ DNA Database Law requires any defendant who is either convicted or received a disposition of court supervision for, completing or attempting to complete a qualified offense to submit a DNA sample to the state’s DNA database. Qualifying offenses include conviction of any felony or crime that requires registration as a sex offender.
The DNA Database Law was expanded in 2012 to require that any suspect arrested and indicted for first-degree murder, home invasion, predatory criminal sexual assault of a child, aggravated criminal sexual assault or criminal sexual assault submit a DNA sample within 14 days of the indictment for inclusion in the database. That means a suspect may ultimately be acquitted, or the charges dismissed before trial, but his DNA has already been taken and placed in the state database.
In cases where a link is made in reverse – DNA evidence helps locate a suspect the police otherwise had no way of finding – the match is usually sufficient to persuade a judge to grant a full search and arrest warrant, which may lead the police to uncover other evidence of a crime.