The Advocate

Fall 2011

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The Use of Familial DNA Evidence in Criminal Prosecutions in Maryland

by Michael J. Palisano

The use of DNA evidence in criminal prosecutions has attracted much attention in recent years due to improved technology and DNA evidence used in high-profile convictions and exoneration of convicted criminals.  Recently, DNA evidence was used to find and convict Aaron H. Thomas, the man suspected to be the so-called “East Coast Rapist,” who attacked six women in Prince George’s County from 1997 through 2001.1  DNA evidence has even been central to the plot of a few primetime dramas, most notably CSI

A particular type of DNA evidence, familial DNA evidence, has also been used to apprehend criminals in high profile cases.  A familial DNA search involves the comparison of a sample taken from the crime scene with DNA profiles stored in a criminal DNA database.  If there is no exact match, the search parameters are expanded to identify a close family member of the perpetrator.2  For example, familial DNA was used to apprehend Dennis Rader, the “BTK killer.”  There, Wichita police were able to positively identify Mr. Rader after first obtaining DNA samples taken from his daughter at a doctor’s appointment.  Familial DNA was also used in California to apprehend the Grim Sleeper killer in 2010.3 

Familial DNA has also been used to exonerate wrongfully incarcerated individuals.  In North Carolina, Darryl Hunt was convicted of a rape-murder.  In 1994, with the improvement of DNA technology, Hunt was ruled out as the perpetrator, but the court refused to grant a retrial until a familial search provided a close match to another inmate, who happened to be related to the actual perpetrator.4 

Maryland and the District of Columbia are the only United States jurisdictions that have banned the use of familial DNA searches in investigations and prosecutions.5  Maryland was the first jurisdiction to pass the ban in 2008, followed by the District of Columbia. Conversely, California, New York, Colorado, Florida, and Virginia have adopted laws to allow limited use of familial DNA investigations. Many other states allow familial searches without legislative imprimatur.

So why has Maryland outlawed the use of familial DNA when so many other jurisdictions are moving towards the use of familial DNA searching?  Maryland’s movement to ban familial DNA searches was led by Stephen B. Mercer, then in private practice and now the Chief of the Forensics Division of the Maryland Office of the Public Defender.  The reasons for Maryland’s ban mirror those considered by the United Kingdom.  The United Kingdom has allowed use of familial DNA since 2002; however, in 2009, the European Union’s Court of Human Rights held that the storage of familial DNA violated the EU’s privacy guarantees.

Similar privacy concerns surround use of familial DNA in the United States.  Fourth Amendment jurisprudence allows DNA to be taken from convicted felons and stored in a national DNA database maintained by the FBI (“CODIS”) for the purpose of identifying perpetrators of future crimes.6  Because convicted felons lack any reasonable expectation of privacy, they also lack standing to pursue a claim for violation of their Fourth Amendment right to privacy.7  As a result, all 50 states mandate the collection of DNA from convicted felons.8

However, those who have not been convicted as felons have Fourth Amendment privacy rights that most courts have held stand in the way of involuntary DNA collection.  As a result, courts are divided on whether to allow mandatory testing of arrestees.  Some courts have held that taking DNA from arrestees constitutes an illegal Fourth Amendment search, lacking the requisite probable cause, while others have held that taking DNA from certain categories of arrestees is constitutional if taken for identification purposes, such as fingerprinting, which does not require individualized suspicion under the Fourth Amendment.9  Courts that have approved the taking of DNA from arrestees have expressed concerns about the use of certain portions of the genetic code, which do not provide personally identifying sequences, but rather show certain familial traits which could be used for a familial DNA search.10

Collection and use of familial DNA, however, take privacy concerns even further.  By securing familial DNA, investigators come to possess DNA of people who are not convicted criminals or even suspects – they are merely family members of those who have been convicted or arrested, or even just suspected of having committed a crime.  The probable cause standard is not met to justify the collection of this DNA. 

Additionally, the risk of disproportionately impacting particular races has played a role in Maryland’s decision to ban the use of familial DNA.  Because the majority of known DNA samples in the Maryland CODIS database come from African-Americans and Hispanics, allowing use of familial DNA searches would likely disproportionately impact those communities, over other demographics that comprise smaller percentages of Maryland’s prison population.  Other states and jurisdictions that allow use of familial DNA have recognized these concerns and have developed safeguards to protect the identities of identified family members.

Despite these concerns, the argument has been made that the DNA of innocent people is already stored in the CODIS database because the DNA of siblings is nearly identical.  In effect, an innocent woman’s DNA is legally seized and documented by the government when her evil twin commits a crime and has her DNA routinely taken after being convicted, because the DNA of the innocent twin is identical to her sister’s.  It has also been argued that DNA can be obtained by “abandonment,” as it can be left by an action as simple as a handshake.  The Maryland Court of Appeals held, in Wilson v. State, that even if DNA is obtained by trickery or deception by police, it can be freely used in any prosecution.11  By this method, the police in Buffalo, New York used DNA taken from the water glass used by serial rapist and murderer during dinner with his wife to apprehend him.  A discarded cigarette, following a court appearance, was used to apprehend Aaron Thomas.  The Supreme Court held that DNA left in a public place is “abandoned” and can be taken by the policy and used in a prosecution.  However, police seizure of DNA that is “abandoned” in a public place still requires a showing of probable cause. 

Some legal experts, while acknowledging the potential for bias, have recognized the scientific value of DNA evidence in crime prevention, and have called for the entry of every U.S. citizen’s DNA into the database in order to ensure fairness.12  Although fairness would be increased with this approach, it would also eliminate any expectation of privacy in one’s own genetic code. The fundamentals of Fourth Amendment search and seizure jurisprudence would have to be reformulated to allow for the systematic taking of DNA from every individual born in the United States.  Moreover, this approach would also not account for crimes committed by non-citizens, as the database would include DNA only from citizens.

In sum, while limited use of familial DNA for the purpose of identifying the perpetrators of crimes may be permissible under the U.S. Constitution, it is not currently allowed in Maryland.  Use of such evidence must be carefully balanced against the obvious privacy concerns that would attend its more widespread use.  Like any powerful crime prevention tool, familial DNA evidence has the potential of being abused and Maryland has sought to avoid this by preemptively outlawing its use. 


Michael J. Palisano can be reached by email at

1 Josh White & Maria Glod, East Coast Rapist Caught In Connecticut, Authorities Say, Wash. Post, March 4, 2011.

2 Fitzhugh Cantrell, Familial DNA Database Searching,  Spring/Summer Edition, J. Pub. Inquiry 24, (2010).

3 Dennis Romero, Grim Sleeper Serial Murder Case Wasn’t First To Rely On ‘Familial DNA: BTK Killer Was Caught That Way, The Informer, Los Angeles Times, (July 13, 2010, 11:07 AM),

4 Jules Epstein, “Genetic Surveillance:” The Bogeyman Response to Familial DNA Investigations, 2009 U. Ill. J.L. TECH. & POL’Y 142, 171 (2009).

5 Md. Code. Ann., Pub. Safety §2-505(b)(1) (LexisNexis 2011).

6 Epstein, infra note 5, at 156.

7 Jeffrey Rosen & Mitchell R. Morrissey, Discussion, How Far Should The DNA Dragnet Go?, N.Y. Times, July 15, 2010.

8 Epstein, infra note 5, at 154.

9 Compare, In re Welfare of C.T.L., 722 N.W.2d 484, 486 (Minn. Ct. App. 2006) (holding that taking such DNA would require a warrant) with Anderson v. Commonwealth, 650 S.E.2d 702, 706 (Va. 2007) (concentrating on the use of DNA for identification purposes).

10 U.S. v. Weikert, 504 F.3d 1, 16 (1st. Cir. 2007).

11 Wilson v. State, 752 A.2d 1250, 1272 (Md. 2000).

12 Akhil Reed Amar, A Search for Justice in our Genes, THE NEW YORK TIMES, May 7, 2002, at A31.


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