The DOJ interim policy says that if a suspect is identified after a genetic association has occurred, STR DNA typing must be performed, and the suspect’s STR DNA profile must be directly compared to the forensic profile previously uploaded to CODIS. This comparison is necessary to confirm that the forensic sample could have originated from the suspect. The policy is internal guidance for DOJ agencies and does not say that an arrest may be made on the genealogy lead alone.

The Department’s policy ... provides the first comprehensive guidance to law enforcement on the use of FGG. It states that once a genetic association generates a lead, law enforcement can use that lead to advance the investigation using traditional investigative and genealogical methods. The policy also says that before FGG is used, all other available techniques, including a search of CODIS, must be exhausted.

The interim policy is composed of nine sections that guide the use of forensic genetic genealogy by law enforcement. It outlines limitations on the use of genetic association to make arrests and the case criteria needed to employ the technique. The policy is primarily internal guidance for the DOJ.

In the event there is no forensic STR DNA profile for a direct match to a suspect reference sample, a SNP panel will be required for comparison between a suspect reference sample and the forensic sample(s). This indicates that after an investigative lead, investigators still need a direct comparison between the suspect reference sample and the crime-scene sample rather than relying on the genealogy lead alone.

Investigators and prosecutors should confirm that the DNA of a suspect who is identified through the familial searching process possesses a DNA profile that exactly matches the DNA left by the alleged perpetrator. To do this, a reference sample must be collected from the suspect after the familial search has been completed. Law enforcement must determine whether and how to collect a DNA sample from a familial search suspect… DNA samples… can be collected through methods including (1) consent of the subject, (2) a search warrant supported by probable cause, and (3) an abandoned sample. A familial DNA search result is only a lead that is then followed up and investigated until a DNA sample of the suspect is obtained and tested. It is those results—those of the suspect—that are generally used in court, not the familial DNA match.

If there is a candidate match in the Convicted Offender or Arrestee Index, the laboratory will go through procedures to confirm the match and, if confirmed, will obtain the identity of the suspected perpetrator. The law enforcement agency can use this documentation to obtain a court order authorizing the collection of a known biological reference sample from the offender. The casework laboratory can then perform a DNA analysis on the known biological sample so that this analysis can be presented as evidence in court. Items taken directly from the suspect are considered deduced suspect samples, not forensic unknowns, and are not eligible for upload to NDIS.

Discussing familial searching and Fourth Amendment law, the article notes that: "In some jurisdictions, a search warrant issued on the basis of a showing of probable cause is required to conduct a reasonable search. In others, the justification for a search can be established with reasonable suspicion or suspicionless cause." It further explains that Colorado authorizes "nontestimonial identification orders, allowing law enforcement agencies to obtain DNA samples based on suspicion lower than probable cause. Courts may issue nontestimonial identification orders for the collection of various specimens, including fingerprints, blood, urine and hair." This shows that obtaining a suspect’s DNA may be done under special statutory procedures rather than being a categorical prerequisite to arrest in all cases.

Once a suspect is identified via investigative genetic genealogy (iFGG) and relevant police work, confirmatory testing must be done using STR profile direct matching. The procedure is similar to the initial steps of preliminary investigation, only that the biological sample is now collected from a suspect identified from iFGG. Confirmatory matching requires a direct match between the suspect's and forensic sample's STR profile data, failure of which means exclusion of the suspect from further investigation. The purpose of iFGG is only to generate suspect investigational leads and not to confirm the perpetrator's identity.

This law review article explains that a familial DNA search "uses a partial STR match to generate investigative leads from the DNA of a suspected criminal’s relative." It situates familial and forensic genetic genealogy searches within the broader Fourth Amendment framework: "A Fourth Amendment search is valid when conducted within the scope of a warrant issued on the basis of probable cause… The Court, however, has also recognized that absent a warrant, Fourth Amendment protections can vary depending on the overall reasonableness of the search." The article treats the partial match and subsequent investigation as part of the probable cause analysis; it does not assert a universal requirement that officers must first obtain and test the suspect’s own DNA to confirm an exact match before an arrest is lawful.

Familial searching is not required prior to proceeding to FGG, unless mandated by the awardee’s state. Investigator and prosecutor concurrence will be obtained prior to proceeding with FGG. The document also requires that a STR profile associated with the perpetrator must have been searched in CODIS and yielded no probative hits before proceeding.

The sufficiency of probable cause to arrest a suspect will largely depend on the extent of genetic and nongenetic investigative information that links a particular close relative of the database qualifying person to the alleged perpetrator of the crime. A familial DNA search is not sufficient by itself to establish probable cause. Familial DNA searches simply identify “potential” relatives of an alleged perpetrator. A familial DNA search result is only a lead that is then followed up and investigated until a DNA sample of the suspect is obtained and tested.

Unless and until it is determined that a suspect’s DNA profile matches that of the single source forensic sample recovered from the crime scene, law enforcement may only interview a suspect identified by familial DNA testing if that suspect is first told he is a relative of someone for whom law enforcement has obtained a partial match in an unsolved crime and that such a match is not conclusive proof that the DNA recovered from the unsolved crime belongs to the suspect. Law enforcement is then required to give Miranda warnings to the suspect before questioning him, whether or not the suspect is in custody. Any statement obtained in violation of this provision shall not be admissible at any judicial proceeding.

Familial DNA testing should use only forensic databases of convicted persons, and not also forensic databases of persons who are merely arrested. If a person is investigated by police solely because they are a close relative of a convicted person who is a close match to the crime-scene DNA, police should need a warrant based on probable cause to seize the investigated person’s DNA, either forcibly or through so-called “found” DNA, such as that left on a coffee cup. The ACLU of Illinois opposes familial DNA testing, but if it is going to be used, it recommends these protections.

Critics argue that the Fourth Amendment bars law enforcement from running warrantless familial DNA searches using consumer databases, even among partial matches with direct-to-consumer users. On that basis, this Article argues against any ban on, or categorical constitutional or statutory rule requiring, probable cause for law enforcement to conduct familial DNA searches. Furthermore, Part Four concludes that courts should not extend Carpenter to create a categorical warrant requirement for familial DNA searches of police databases or DTC databases where an initial user has given consent to law enforcement access.

Law enforcement may use information gathered from a partial match in an investigation. Whether law enforcement will use the data, though, depends on the state’s laws. Some states allow reporting of partial DNA matches, while others do not. Other states allow the reporting of partial match information but do not allow explicit searches for familial DNA. Many states have not formally adopted procedures for familial DNA searches. Only a few states explicitly allow law enforcement officials to use familial DNA searches. As noted by the OJP, most states leave the decision to agencies rather than their legislatures.

The Montana Act is simple: law enforcement is required to obtain a search warrant to search consumer DNA databases unless the person in question previously gave informed consent to public or law enforcement access. The Maryland Act raises the bar higher. It mandates that law enforcement obtain judicial authorization before initiating a forensic genetic genealogical search. This authorization will only be given if the forensic sample satisfies a rigorous set of criteria… As for the databases, the searches may only be conducted using commercial or publicly available databases that provide users notice of and seek consent for law enforcement use of their data.

The DNA testing technique uses genetic material from relatives to track down a suspect and solve crimes. Investigators upload crime scene DNA into a database to seek out relatives of the alleged culprit. In California, once a partial match is found, traditional police work is used to identify potential suspects, who are then asked to submit their own DNA or are tracked until they leave behind “discarded” DNA on items such as a cup or spoon. That DNA is then compared to the crime scene DNA to see if there is a full match, which can lead to an arrest.

Most policies require that the forensic unknown DNA profile is a single-source, complete profile produced after analyzing the crime scene sample. Law enforcement officers may not perform Familial Searches unless they meet the case and sample requirements, as well as any other requirements prescribed in a search policy. Nonetheless, Familial Searching raises the question of whether it is fair for someone who has committed no crime to become a virtual suspect because a relative’s DNA is on file.

Under existing New York State regulations, the DCJS may release the identity of an individual whose DNA profile is stored in the state’s databank when, using existing DNA analytic protocols, there is a partial match between that individual’s DNA and biological evidence at a crime scene. Practically speaking, familial searching would only be performed if the comparison of the forensic DNA profile with the known offender/arrestee DNA profiles has not identified any matches to any of the offenders/arrestees. Existing law does not permit the Commission on Forensic Science to authorize familial DNA searching; nor does DCJS possess such authority.

DoJ guidance discussed here emphasizes that forensic genealogy is used to generate leads, and that the very last step is confirmatory DNA analysis through direct STR testing. The speaker says this confirmatory step leads to probable cause for an arrest, distinguishing it from the genealogy search itself.

This form of testing allows law enforcement officials to identify family members of people who leave DNA at a crime scene in order to better track them down. Once investigators identify a possible suspect through familial DNA, they will often seek that person’s DNA directly, either through a warrant, consent, or discarded items, to confirm whether the suspect’s DNA matches the crime scene sample. Only after this confirmatory testing yields a match is DNA evidence typically used to support charges.

The unknown DNA profile must meet these requirements: be a single source or fully deduced single source profile originating from a mixture; appear to have a direct connection with the putative perpetrator of the crime… reside in the NYS DNA Databank and, therefore, meet the specific sample requirements for inclusion in CODIS; have been searched against DNA profiles of offenders contained in the State DNA Databank. These conditions govern when and how familial DNA searching can be used as an investigative tool in New York State.

This Sidebar provides legal background on DNA identification and the Fourth Amendment, with particular emphasis on the 2013 Supreme Court case Maryland v. King. In King, the Court upheld the constitutionality of collecting and analyzing DNA from individuals arrested for serious offenses, treating DNA collection at booking as similar to fingerprinting and photographing for identification purposes.

Familial DNA searches and investigative genetic genealogy are generally understood in practice and policy as tools to generate investigative leads, not as standalone proof of identity. In jurisdictions that use these techniques, law enforcement typically seeks to obtain the suspect’s own DNA via consent, warrant, or collection of abandoned samples for confirmatory testing before relying on DNA evidence in charging decisions or at trial, but specific arrest procedures and thresholds of probable cause vary by state law and are not governed by a uniform national requirement.