In the case of People v. Marquez, 2019 Cal. App. LEXIS 48 (4th Dist. Jan. 15, 2019), the California Fourth District Court of Appeal held that the 2006 collection of Daniel Joseph Marquez’s DNA sample was unlawful under the Fourth Amendment, but also concluded that the trial court properly admitted 2008 DNA evidence from a separate incident in 2008 that matched the 2006 evidence under a well-established exception to the exclusionary rule: the attenuation doctrine.


In October 2006 in Ventura County, Marquez was arrested on a drug possession offense. Authorities collected his DNA sample and entered his DNA profile into the California Department of Justice DNA Data Bank, but without Marquez’s consent. Marquez was never charged for the drug offense, but pled guilty in September 2007 to a different felony charge.  He was placed on probation and ordered to submit to DNA testing under Penal Code section 296.

In 2008, Marquez attempted to rob a bank and fought off bank managers before he fled. However, he left the leather organizer which contained the banks would-be-stolen money as well as a pair of glasses.  From these items, investigators obtained DNA evidence.  That evidence matched Marquez’s DNA profile in the database (a “cold hit”), and learned Marquez was on felony probation and subject to a search and seizure condition. Police contacted Marquez, and with his voluntary consent they collected another DNA sample, which matched the DNA evidence from the robbery.

The trial court denied Marquez’s motion to suppress the DNA evidence, and a jury convicted him of two second degree robbery counts and a related offense. The trial court held that Marquez’s 2006 DNA sample was lawfully collected.  Alternatively, the trial court held that the 2008 DNA evidence was “attenuated” because the September 2007 order for Marquez’s DNA testing was an “independent intervening event.”  The court sentenced Marquez to 25 years to life in state prison, plus an additional 15 years for three alleged prior serious felony convictions.  The Fourth District Court of Appeal subsequently affirmed, holding that the 2006 DNA collection was lawful under the Fourth Amendment to the United States Constitution. In 2018, the California Supreme Court ordered the Fourth District to vacate its previous decision and reconsider the case in light of its decision in People v. Buza.[1]


Marquez had argued that the 2006 DNA collection violated the Fourth Amendment and the derived evidence should have been suppressed. Looking at the warrantless collection of Marquez’s DNA in 2006, the Fourth District explained that a warrantless search is presumptively unreasonable under the Fourth Amendment,[2] unless the prosecution proves by a preponderance of the evidence that the search falls within an exception to the warrant requirement.

The Court of Appeal explained that the United States Supreme Court in Maryland v. King[3] crafted a new Fourth Amendment exception to the warrant requirement. Following an arrest supported by probable cause, the collection of a suspect’s DNA by taking a cheek swab during a routine booking procedure was established as a valid exception to the warrant requirement (King also held that a DNA cheek swab—like any invasion of the body—was a “search” within the meaning of the Fourth Amendment).  Moreover, the California Supreme Court in Buza[4] held that the collection of a DNA sample is lawful when a suspect is validly arrested on probable cause to hold for a serious offense as part of a routine booking procedure.

Here, the Fourth District held that the prosecution failed to prove by a preponderance of the evidence that Marquez was validly arrested in 2006 because there was nothing in the record to indicate that Marquez’s 2006 arrest was supported by probable cause; no charges were ever filed and there was nothing indicating suggesting Marquez was guilty of any “serious” offenses. Nor was there any record that his DNA was collected as part of a routine booking procedure.  The Court observed that Marquez’s DNA was collected four days after his arrest, a delay that was left unexplained by the prosecution.  The Court accordingly found that the prosecution failed to establish that the 2006 DNA collection of Marquez’s DNA sample fell within an exception to the warrant requirement.  Thus, the Court concluded that the 2006 warrantless search by way of the DNA collection violated the Fourth Amendment.

The Fourth District next considered whether the 2008 DNA evidence should have been excluded. The Court explained that the “exclusionary rule” generally prohibits evidence obtained in violation of the Fourth Amendment from being used in criminal trials.  (Mapp v. Ohio (1961) 367 U.S. 643, 650–651.) However, the United States Supreme Court has “repeatedly rejected the argument that exclusion is a necessary consequence of a Fourth Amendment violation.”[5]  One such exception to the exclusionary rule is the attenuation doctrine. Under this doctrine, exclusion of the evidence is not required when the connection between the unlawful activity and the evidence in question becomes “‘so attenuated as to dissipate the taint’”[6] of the unlawful activity.  The Supreme Court has described three factors that determine whether the attenuation doctrine should be applied: (1) how much time elapsed between the unconstitutional conduct and the discovery of evidence; (2) the presence of intervening circumstances; and (3) the purpose and flagrancy of the official misconduct.

Here, the Court found that a substantial period of time of about two years had elapsed between the unlawful collection of Marquez’s DNA sample in 2006 and the lawful collection of DNA evidence in 2008. The Court also found that Marquez’s three (or more) arrests and order to submit to DNA testing on each occasion were intervening circumstances supporting attenuation from the 2006 collection. Likewise, the fact that at the time of Marquez’s 2008 DNA collection, he was on felony probation and consented to the cheek swab raised another intervening circumstance. Finally, the Court found a lack of evidence concerning flagrant official misconduct in obtaining the 2006 DNA sample.  Considering these three factors, the Court of Appeal therefore concluded the 2006 unlawful collection of Marquez’s DNA sample was sufficiently attenuated from the 2008 “cold hit” linking Marquez to the robbery and the lawful 2008 collection of his DNA sample.  Thus, the Fourth District concluded that the trial court properly admitted the 2008 DNA evidence under the attenuation doctrine.  Accordingly, the Court of Appeal affirmed as to these matters, though the Court remanded to the trial court for other reasons not relevant here.


The Fourth District in Marquez builds upon the legal foundation laid by King and the state supreme court in Buza that further secures DNA collection by police as a practice and fleshes out the legal framework and limiting conditions of DNA’s use in court.  Looking at the 2006 DNA collection here in isolation, it is clear that probable cause was lacking to justify the DNA collection, as was evidence of the collection as part of a routine booking procedure, especially considering the unexplained four-day gap between arrest and collection.  The failure to support these two prerequisites to proper DNA collection rendered taking the sample in 2006 legally supportable.  Only by application of the attenuation doctrine was the Court able to determine that, ultimately, there was no Fourth Amendment violation and the 2006 sample could be utilized to convict Marquez of the 2008 offense.  Agencies should continue to stay abreast of these significant cases as this area evolves, and advise their officers accordingly.

As always, if you wish to discuss this matter in greater detail, please feel free to contact me at (714) 446–1400 or via email at jrt@jones-mayer.com.

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[1] 4 Cal.5th 658 (2018).

[2] Vernonia School Dist. 47J v. Acton, 515 U.S. 646, 652–653 (1995).

[3] 569 U.S. 435, 465 (2013).

[4] For more on Buza, please refer to Client Alert Vol 33. No. 10.

[5] Herring v. United States, 555 U.S. 135, 140 (2009).

[6] Murray v. United States, 487 U.S. 533, 537 (1988).