Brandon Mayfield: Forensic Failures

Kenshin Y
53 minutes ago
4 min read

On March 11 2004, terrorist bombings on passenger trains in Madrid killed 191 people and injured hundreds more.

In a desperate, international investigation to find the perpetrators, law enforcement agencies used forensic evidence, including latent fingerprints, to identify suspects.

One of those prints was wrongly connected to an Oregon attorney, Brandon Mayfield, leading to him being secretly arrested and detained by the FBI.

Brandon Mayfield's case prompted lawsuits, policy reviews, and debates regarding the reliability of evidence, serving as a prime example of how forensic mistakes and bias in law enforcement can significantly impact legal outcomes and personal freedoms.

Background: Brandon Mayfield & the Madrid Bombings

Brandon Mayfield was born on July 15 1966. He was an American lawyer practising family law in Beaverton, Oregon. Before becoming a lawyer, Mayfield was also a US Army Reserve and Army officer.

Mayfield had converted to Islam in the 1980s and he was an active member of his local mosque. He also had four children.

As a lawyer, Mayfield had represented many clients, including one indirectly related to terrorism crimes, the Portland Seven. This is an important detail that would later appear in FBI files.

Mayfield's fingerprints and a misdemeanour arrest as a teenager unrelated to terrorism were also in the FBI database.

March 11, 2004 Madrid Bombings

Terrorist train bombing near Atocha Station, Madrid, March 11 2004

On March 11, 2004, multiple bomb explosions occured in four commuter trains during the morning rush hour in Madrid, killing 191 people and injuring more than 1500.

The Spanish National Police retrieved forensic evidence, including fingerprints on a bag of detonators. Through Interpol, Spanish authorities shared images of these prints with the FBI to help identify suspects.

The Tragedy: What Happened and How Mayfield Was Caught

When Spanish authorities sent the digital photographs of the prints on the detonator bag to the FBI, they were entered into the database. No exact matches were found so a second search was performed, prompting the database to return 20 possible matches whose known prints had common features with the fingerprints on the detonator bag. One of these was Brandon Mayfield.

The FBI's latent print examiners in Quantico initially claimed that the print was a “100% match” to Mayfield’s fingerprints.

Despite the Spanish National Police's concerns that their own comparison did not support the match to Mayfield, and that the prints actually matched another man, the FBI went ahead and conveyed the Spanish findings to a federal judge.

Authorities continued their surveillance and ultimately gained a material witness warrant to detain Mayfield.

Mayfield was arrested at his law office on May  6 2004, under a material witness statute instead of criminal charges. This meant that Mayfield was detained because the police claimed that he could provide crucial testimony, not because prosecutors believed he committed a crime.

The FBI held him initially under a false name in a Portland county jail for two weeks with limited access to family or legal representation.

His family had always maintained his innocence, saying he had not been out of the country for more than a decade.

During this time, the FBI conducted covert searches of Mayfield's home and law office under the “sneak and peek” provisions of the Patriot Act and obtained warrants for electronic surveillance.

They gathered computers, documents, including his children's Spanish language papers, hygiene items for DNA swabs, and more.

Meanwhile, Spanish authorities had already matched the print to an Algerian, Ouhnane Daoud. Once the FBI acknowledged this, Mayfield was released on May  20 2004, and the case against him was dismissed days later.

Brandon Mayfield after his release from being falsely imprisoned

Psychology of Bias and Forensic Failures

The Brandon Mayfield case highlighted that forensic science is not always objective.

Fingerprint comparison had long been considered infallible, but it relies heavily on human interpretation.

Experts have discovered that cognitive biases can affect examiners, particularly when they are aware of contextual information like a person's religion or suspicions of terrorism.

In contrast to automated DNA matching, fingerprint analysis lacks fully standardised and reliable criteria that helps to determine a positive match, which could lead to errors.

Several issues likely contributed to Mayfield's false imprisonment:

Confirmation bias: Once Mayfield’s prints were brought to attention, examiners subconsciously interpreted the evidence as a confirmed match.
Contextual pressure: After 9/11, the urgent need to arrest terrorist suspects quickly in order to calm society may have increased, which may have reduced critical investigation.
Ignoring conflicting evidence: FBI examiners ignored the Spanish authorities' strong disagreement with the latent fingerprint's similarity to Mayfield's when they provided it to the courts.

The US Department of Justice Office of Inspector General later concluded that Mayfield’s religion did not play a part in the investigation. However, some analysts argue that contextual information, such as Mayfield's faith and legal work, strengthened investigators’ confidence in his involvement in the bombings.

Aftermath: Lawsuit & Challenges

Mayfield speaking in court for settlement

After his release, Mayfield filed a lawsuit claiming there were violations of his constitutional rights, including unlawful detention, invasion of privacy, and excessive surveillance.

In November 2006, the US government agreed to a reported $2 million settlement and issued a formal apology to Mayfield.

"After facing the weight of the government, things will never be quite the same for any of us, my wife, my children or myself," Mayfield claimed.

As part of the settlement, Mayfield was allowed to continue legal challenges to the provisions of the USA Patriot Act, particularly those allowing secret searches and surveillance without probable cause.

In 2007, a district court ruled that certain Patriot Act provisions violated the Fourth Amendment. However, this decision was later overturned on procedural grounds, and the US Supreme Court declined further review in 2010.

The Mayfield case helped promote internal FBI reviews and brought awareness to the trustworthiness of latent print identification.

Critics point to this incident as proof that quality control for fingerprint analysis must improve and bias needs to be minimised through standardised procedures to avoid such serious errors in the future.