The story unfolds like a hybrid horror or science fiction film: a serial killer called the Grim Sleeper preys on prostitutes and drug addicts, murdering them and disposing of their bodies in dumpsters and alleyways in a south Los Angeles neighborhood. The deranged man kills at least seven women in the mid-1980’s and then seemingly disappears, only to reemerge for a second killing spree twelve years later. Using a controversial technology only employed in two states, forensic scientists help the LAPD apprehend the murderer. By comparing DNA found at the murder scenes to the DNA of prisoners in state custody, the scientists discover that the son of the serial killer has recently been convicted on a weapons charge. Based on the DNA match, investigators scour birth records and geographic data and confirm that the convicted felon’s father fits the profile of the Grim Sleeper. Detectives follow the suspect until, one fateful day at a pizzeria, the killer discards a piece of pizza crust and a paper plate from which scientists retrieve DNA that matches the DNA left behind at the crime scenes.

On July 8, police charged Lonnie Franklin, Jr. with ten counts of murder. Mr. Franklin is a 57-year old mechanic residing in the middle of the same Los Angeles neighborhood where the Grim Sleeper committed his crimes. Although the case of the Grim Sleeper has been significant to locals for years, the fact that law enforcement apprehended the killer by using controversial familial DNA testing has recently made the story newsworthy around the world. While the story is the poster child that proponents of the technology have been waiting for, it is also likely to inspire intensified debate about the technology’s legality.

Whereas crime labs generally search DNA databases for a perfect match to DNA found at the crime scene, software running a familial DNA test analyzes the DNA in the database to find a partial match to the crime scene DNA. Although strangers may have some genetic markers in common, familial DNA testing locates relatives by looking for a greater number of similarities. The technology can also be used to find close male relatives such as brothers, or fathers and sons since closely related male relatives possess an identical Y chromosome. Once investigators find a relative’s DNA in the database, they can use that information to track down the perpetrator of a given crime. Experts have estimated the success rate of familial DNA testing at 10% to 14%.

While the moderate success rate is laudable, the legality of the technology is unclear. As we all well know, the Fourth Amendment secures individuals against unreasonable searches and seizures, and requires that warrants be supported by probable cause. Assuming a search of an arrestee’s DNA is warranted for the purpose of determining whether the suspect committed a particular crime, is it also reasonable to search that DNA again later for evidence that a relative may have committed a different crime? Once investigators fail to find a perfect match in the database, they know that no individual in the database committed the crime, so isn’t it inherently unreasonable to run a second search of a given convict’s DNA? Privacy advocates would argue that it is.

Furthermore, as Jeffrey Rosen points out in a comprehensive article about the issue of familial DNA testing, when Congress established the Combined DNA Index System (CODIS), it arguably did not intend the database to be used for familial searches. The justifications courts have accepted for collecting and keeping the DNA of convicted criminals do not support using a convict’s DNA to find other possible criminals in his family. For example, the Ninth Circuit in U.S. v. Kincade opined that keeping the DNA of criminals on probation was legal because the convicts had a decreased expectation of privacy, and because retaining probationers’ DNA could deter further criminal activity.

In any event, catching a serial killer is obviously a good thing. If familial DNA testing is accurate and leads to the apprehension of a guilty party who otherwise may not have been caught, perhaps we are willing to tolerate the invasion of privacy.

Emily Beverage

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2 Responses to Catching the Grim Sleeper, Reawakening the Debate Over Familial DNA Testing

  1. Mike says:

    Josh, it seems to me if you believe the initial taking of the DNA is an invasion of privacy, any subsequent search of the database would be tainted by that initial invasion, much like introducing evidence obtained in violation of the 4th Amendment.

  2. Josh says:

    Would the search of data that is already in the database be an invasion of privacy? It seems like once the DNA is taken from the prisoner, which certainly is an invasion of privacy, the government has control over the database and argubly should be able to run as many searches as it pleases.