Monthly Archives: February 2011

How Successful Are Kinship Searches (aka Familial Searches)?

Kinship analysis refers to comparing DNA profiles from different individuals to see if one individual might be a close relative of another. It is done all the time in child-support and missing-remains cases. It is done in criminal cases when a rape victim has a child or aborted fetus.

Using the same principles of genetics, kinship searches can be conducted in a law enforcement database of identifying DNA profiles. For brevity, we can call the convicted offenders (or, in some jurisdictions, arrestees) whose DNA profiles are recorded in a database “database inhabitants.” The profile derived from a crime-scene can be compared with all the database profiles to see (1) if a database inhabitant’s profile is an exact match (the usual “cold hit”) or (2) if there is a close enough match (as shown by kinship analysis) that the crime-scene DNA may have come from a very close relative of a database inhabitant. One group of scientists (Bieber et al. 2006) estimated that kinship matching could generate thousands of useful investigative leads nationally. However, the technique is almost never used, leaving proponents and opponents to rely on their choice of anecdotes about its value and accuracy.

A case in point is a recent law review article that emphasizes “one revealing fact: [Denver’s District Attorney, Mitch Morrissey‘s] familial searches did not work. None of the three matches turned out to point toward a relative, much less the source, of the actual crime-scene sample. . . . [I]t failed in three separate cases . . . .” Erin Murphy (2010).

However, these searches did not use a matching strategy designed and optimized to detect kinship. According to Moreau-Horwin (2011):

In 2009, Morrissey launched a familial search research project with the Denver Police Department. A familial search software program was designed by the DA’s office and the Denver Police Crime Lab. The program would only extend to siblings and parents. When a hit is made, family members could not be questioned unless investigators isolate a suspect using traditional detective work.

This software program resulted in the first case ever to use a deliberate familial search in the United States. In February 2008, several cars were burglarized in a Denver apartment complex. In one car, blood stains were left on the front seat. After extracting the DNA profile, the police ran it through the DNA database, but did not get a match. They then processed the sample as a familial search and a brother of the offender was identified. This led law enforcement to 21 year-old, Luis Jaimes-Tinajero. Police received a court order to take his blood and it was a perfect match to the evidence sample. Jaimes-Tinajero pleaded guilty on September 10, 2009 to criminal trespass and was sentenced to two years probation. Although this case was only designed to test the new familial search software, it would probably have received more publicity had it led to the arrest of a rapist or murderer and not a car burglar who apparently stole only $1.40 in change. 1/

So, is Morrissey’s record 0 for 3 or 1 for 1? It is neither. Surely, there were many cases in which the Denver kinship searches drew blanks or false leads. But the usual, full-match searches do not always produce cold hits either. The latter hit rate depends on the fraction of perpetrators of the crimes who are “database inhabitants.” The former hit rate is much more complicated. It depends on (1) sensitivity–that is, the ability of the kinship matching algorithm to hit on a true relative of the crime-scene profile source in the database; and (2) prevalence–the proportion of relatives of database inhabitants (a) who commit crimes with DNA traces and (b) who are not themselves database inhabitants. The sensitivity of various algorithms can be estimated (Bieber et al. 2006; Curran & Buckleton 2008), but the prevalence is more uncertain. The known fact that the prison population contains a substantial fraction of close relatives is high might mean that there are many more as yet unidentified relatives engaged in criminal activities. (Bieber et al. 2006).

Until a state implements a well designed form of kinship matching in a large number of cases, however, the real-life efficacy of the technique will not be known. The only reference I have seen so far to such information is in a news report of a study in the United Kingdom which “found that, out of 100 searches, more than a dozen led to a suspect.” (Miguel 2007).


1. Ms. Moreau-Howin is a forensic DNA database consultant who maintains a website, For more details on the successful case from a traditional news source, see, Car Vandal Nabbed Thanks To Brother’s DNA, Nov. 16, 2009, (reporting that Luis Jaimes-Tinajero’s “brother was in the system because of a felony conviction for auto theft” and that the “car was one of many at his Denver apartment complex broken into [that] morning”).

References, Car Vandal Nabbed Thanks To Brother’s DNA, Nov. 16, 2009,, last accessed Feb. 20, 2011

Frederick R. Bieber et al., Finding Criminals Through DNA of Their Relatives, 312 Science 1313 (2006).

James M. Curran & John S. Buckleton, Effectiveness of Familial Searches, 48 Sci. & Justice 164 (2008).

Ken Miguel, The controversies surrounding ‘partial DNA,’ ABC7 News, Nov. 13, 2007,, last accessed Feb. 20, 2011

Raphaele Moreau-Horwin States Using Familial Searches,, last accessed Feb. 20, 2011

Erin Murphy, Relative Doubt: Familial Searches of DNA Databases, 109 Mich. L. Rev. 291 (2010).

DNA Database Trawls and the Definition of a Search in Boroian v. Mueller

In August 2010, the U.S. Court of Appeals for the First Circuit disposed of an argument about the constitutionality of DNA databases that it previously had consciously and conspicuously avoided a few years earlier. In Boroian v. Mueller, 616 F.3d 60 (1st Cir. 2010), this court finally held that the government can keep a convicted offender’s DNA profile in a law enforcement database even after he has paid his metaphorical debt to society.

This outcome is hardly surprising. Long-lasting, collateral consequences of convictions have become commonplace (Pinard 2010), and continuing to trawl for matches to unsolved crimes after a convicted offender is no longer subject to confinement or supervision adds significantly to the power of DNA databases. Nevertheless, the reasoning that the court used to reach this result has come under attack in recent writing, and the court itself tried to reign in the implications of the rationale it employed.

The Case and the Prior First Circuit Law

Martin Boroian was convicted in 2004 of making a false statement to a federal official. For this crime, he spent a year on probation. During this year, he provided (under protest) a blood sample as required by a federal law mandating the inclusion of DNA profiles in the FBI’s national DNA database. In 2008, Boroian sought to have his DNA profile expunged and his DNA sample destroyed. His complaint, filed in federal district court, alleged that the retention and analysis of his DNA profile and sample–after completion of his probation term and without reasonable suspicion of any new criminal activity–violated the Fourth Amendment’s prohibition on unreasonable searches and seizures.

The district court dismissed the complaint. The court decided that even if the facts listed in the complaint all were true, the government was acting constitutionally. First, the court concluded that the government’s retention and periodic accessing of his lawfully obtained DNA profile was not a new search within the meaning of the Fourth Amendment. Second, the court held that although a new analysis of the DNA sample could constitute a separate search under the Fourth Amendment, Boroian’s complaint contained no allegations of a present or imminent analysis of the sample. In short, the district court determined that the government can hold on to the physical evidence Boroian was required to provide as long as it wanted to, and it could use the information it had extracted from the evidence–Boroian’s DNA identification profile–over and over, in checking profiles from new crime-scene DNA samples against Boroian’s (and those of the millions of convicted offenders with profiles in the national database).

The latter proposition seems difficult to deny. On appeal, Boroian did not–and realistically, could not–argue that the law requiring him to provide the sample for the database was unconstitutional. Like every other appellate court to the address this question, the First Circuit has held that the compulsory collection of DNA samples from convicted offenders for computer searchable DNA databases is a reasonable search and seizure. In United States v. Weikert, 504 F.3d 1, 14 (1st Cir. 2007), the First Circuit wrote that:

After careful consideration, we conclude that the government’s important interests in monitoring and rehabilitating supervised releasees, solving crimes, and exonerating innocent individuals outweigh Weikert’s privacy interests, given his status as a supervised releasee, the relatively minimal inconvenience occasioned by a blood draw, and the coding of genetic information that, by statute, may be used only for purposes of identification.

Because the court’s balancing relied heavily on the value of the DNA database in producing “cold hits” to solve crimes, Weikert surely upheld, as constitutionally reasonable, not merely the compelled collection of DNA from offenders while on probation or release, but also the analysis of the samples to extract the numerical DNA profiles, the recording of these profiles in the national database, and the trawls of this database of the DNA profiles extracted from these samples. These trawls, after all, are the raison d’etre of a computer-searchable database.

The only colorable argument against continuing to trawl the database with Boroian’s profile in it was that the balance of interests had shifted in his favor after he had served his sentence. Indeed, the Weikert court had left this question wide open, writing that it was

withholding judgment on whether retaining a former conditional releasee’s DNA profile in CODIS passes constitutional muster. The distinction in status between a current and a former offender clearly translates to a change in the privacy interests at stake. A former conditional releasee’s increased expectation of privacy warrants a separate balancing of that privacy interest against the government’s interest in retaining his profile in CODIS.

504 F.3d at 16.

Boroian’s Reasoning

The court in Boroian, however, refused to undertake this “separate balancing.” Rather than weigh the two sets of interests to decide whether an offender could be forced to surrender his DNA for database trawls after the completion of the sentence, the court now reasoned that the trawls coming at this later stage were not even “searches” within the meaning of the Fourth Amendment. Analogizing DNA identification profiles to “fingerprints or mugshots [that] are routinely retained by the government after . . . sentences are complete,” 616 F.3d at 67, the First Circuit wrote that “we join the other courts to have addressed the issue in holding that the government’s retention and matching of Boroian’s profile against other profiles in CODIS does not violate an expectation of privacy that society is prepared to recognize as reasonable, and thus does not constitute a separate search under the Fourth Amendment.” Id. at 67-68 (footnote omitted). In this way, Boroian repudiated Weikert‘s “dicta that the government’s retention and periodic matching of a lawfully obtained profile after the offender had completed his term of supervised release would require a rebalancing of the relevant government and privacy interests to determine the reasonableness of the search.” Id. at 68 n.6.

In general, rejecting the suggestion that every trawl of information in a database is a separate search that requires independent justification is sensible. Once the government lawfully acquires the information, the marginal invasion of privacy that comes from using it later is minimal. Consequently, the government should not be forced to use the data once, then forget it. Suppose that in executing a valid warrant permitting the seizure of a stolen personal computer with serial number C2011A from a warehouse, government agents observe and record the serial numbers C2013A and C2013C on other computers. A week later, they receive a report of a theft of the PC with serial number C2013A. The warrant did not authorize the agents to compare the numbers a week later, but one of them remembers the number (or looks up the record of the first search), thus linking the owner of the warehouse to the second crime. What meritorious privacy interest can the owner assert to stop the government from checking for a match in the serial numbers? Treating the simple trawl of the stored information as not subject to the strictures of the Fourth Amendment–because it is not a “search”–seems appropriate.

Yet, this mode of analysis creates a puzzle. By invoking a broad no-search doctrine, Boroian avoids even asking the fundamental, prior question of whether the government’s interests justify a system that trawls for DNA matches not only during the sentencing period but indefinitely thereafter. The opinion seems to say that as long as it is clear that the acquisition and use of the offender’s DNA profile for a limited time is permissible, trawls for all time also are permissible.

A recent law review article takes issue with the generally accepted view that “[l]awful collection simply ends the analysis: anything further is fair play.” (Murphy 2010, 1334). But the free reuse of legitimately acquired information is deeply entrenched in established Fourth Amendment doctrine. It follows from the nature of the interests the Fourth Amendment protects. For example, an individual whose DNA profile is in the database–a database inhabitant, so to speak–might well be concerned that later trawls will harm him by exposing him as the perpetrator of an unsolved crime. A later trawl that had this outcome certainly would harm the database inhabitant, but it would not infringe a legitimate interest, let alone an interest that the Fourth Amendment respects. Under “conventional doctrine,” id., the Fourth Amendment does not protect information. It only protects individuals against oppressive methods of acquiring that information. One can decry this “this singular attention on acquisition,” id., but trying to undo it through the Fourth Amendment would be a major task. It harkens back to the days of Boyd v. United States, 116 U.S. 616 (1886), in which the Supreme Court held that a court order for the production at trial of certain papers was a search and seizure, not because of the manner in which the government was acquiring the information, but because of the information itself.


Boroian v. Mueller, 616 F.3d 60 (1st Cir. 2010).

Boyd v. United States, 116 U.S. 616 (1886),

Erin Murphy, Relative Doubt: Familial Searches of DNA Databases, 109 Mich. L. Rev. 291, 3334 (2010).

Michael Pinard, Collateral Consequences of Criminal Convictions: Confronting Issues of Race and Dignity, 85 NYU L. Rev. 457 (2010).

United States v. Weikert, 504 F.3d 1, 14 (1st Cir. 2007).