Tell the Truth & Nothing but the Truth: How Audio is Solving Crimes

By: Danielle Chazen
police technology

In July, a Florida man was charged with the murder of his girlfriend, Silvia Crespo. He claimed it was an accident and that he’d even tried to save her life, reported The Washington Post. Back in November 2015, an Arkansas man was accused of murdering a friend at home. The man claimed it was an accident that happened while he slept off a night of football and drinking, reported CNN

In both cases, the police decided to investigate a key witness: Alexa, Amazon’s voice-activated virtual assistant.

Police sought out evidence of the July crime through a warrant for the audio recordings maintained by Amazon. They believed the attack on Crespo that occurred may be found on the server, but obtaining these recordings opens the door to significant debate. 

Audio and Voice Forensics Uncover The Facts

Sometimes, receiving a recording is all it takes to prove guilt or innocence. Yet not all recordings are made equal, and they’re certainly not all equally trustworthy. That’s where voice forensic and audio forensic experts come in. There’s also a lot of math involved.

“By measuring the time it takes the sound to reach each microphone,” software tools “can estimate the original location,” explained CBC. Further investigations of audio submitted as evidence often occur to ensure a direct recording was provided and that it caught the sound or events authentically.

Accuracy and authenticity are critical. Audio forensics experts are often tasked with figuring out whether an audio file matches the device it was allegedly recorded on. They must consider whether the recording was delivered as is, or some elements were edited out or added in.

Voice biometrics also come into play. Like fingerprints, voiceprints are unique to each person. They are composed of countless elements, and cannot be replicated or confused with another human’s voiceprints. This fact is crucial when considering recordings that contain multiple voices, especially similar ones, that could sound the same to the naked ear. As voice recognition technology grows smarter, ensuring the accuracy of an investigation and its corresponding evidence will become easier.

 Transcribing Audio Files Accelerates Investigations

Another way technology is making law enforcement professionals’ lives easier is by allowing them to search through audio files, so they can easily find the piece of the recording needed to understand where to follow up.

Artificial intelligence has made it possible to get audio files transcribed faster than ever at a high level of accuracy and in a cost effective way. AI-based tools are trained using thousands of hours of content to understand industry terms, past cases and current events. Some providers have human professionals review each transcript in order to deliver up to 99% accurate results. With artificial intelligence, each time the software is used and its transcript is corrected, it becomes smarter.

Law enforcement professionals use transcription software on the go to record notes instead of stopping to write them down while chasing a suspect, which reduces the need to sacrifice accurate documentation. At the office, they can transcribe investigations, testimonies, 911 calls and surveillance materials, among others.

Some professionals process information better when reading it, while others might notice a detail they missed initially while reviewing materials in different formats. Text-based content is also easier to share with colleagues who are collaborating on a case. Finally, audio search is often helpful for law enforcement who must search for and find specific sentences in a sea of evidence.

Could Increased Audio Usage in Law Enforcement Lead to the End of Privacy?

Despite the many benefits of using today’s audio technologies to solve crimes efficiently and accurately, Amazon, who introduced Alexa to the world, was not quick to collaborate with law enforcement.

Amazon’s reasoning? Privacy.

“‘Given the important First Amendment and privacy implications at stake, the warrant should be quashed unless the Court finds that the State has met its heightened burden for compelled production of such materials,’ Amazon’s lawyers wrote in a February memo,” reported CNN in 2017, referring to the 2015 Arkansas murder case.

In July 2019, when law enforcement officials asked for the Amazon Echo files regarding the murder case, Amazon pushed back again. According to The Washington Post, which is owned by Amazon CEO Jeff Bezos, “‘in a statement, Amazon spokeswoman Faith Eischen told The Washington Post that the company ‘does not disclose customer information in response to government demands unless we’re required to do so to comply with a legally valid and binding order.’ She added that the company ‘objects to overbroad or otherwise inappropriate demands as a matter of course.'”

While Amazon’s fight for privacy is likely, at least partially, influenced by its commercial interest and the need to retain customer trust, it brings up a point that is valuable regardless of such interests. Many of us reveal intimate information to the devices that surround us every day. Our privacy, and therefore our safety, becomes more and more vulnerable with each passing year. Tapping into this information without our authorization cannot be an easy decision or process.

Moreover, organizations that partner up with technology companies to accelerate investigations and deliver justice need to take these facts into consideration. It is critical to ensure sensitive information is only shared with providers who have taken real steps to secure privacy, both from cybercriminals and from colleagues who don’t absolutely need the information for their work. Despite the clear argument to protect one’s privacy, technology is empowering law enforcement and the workforce’s ability to solve crimes like never before. 

When Used Correctly, Technology Provides Greater Justice

Using audio in investigations is nothing new, yet as technology advances, it becomes easier to determine the specifics of a committed crime – the how, when, why, and who. As law enforcement professionals tap into the opportunities that the market’s tech tools provide, it is important to keep citizens’ rights in mind. Privacy and security concerns remain of the utmost importance.

When implemented effectively, technological advancements can help make the world a much safer place.