The Chicago Police Department released dash cam video of the Laquan McDonald shooting. Although most dash camera video recordings include an audio track, this did not. Concerned citizens believed that the audio portion of the video recording was intentionally deleted or altered. We previously explored why there could be an absence of audio during these videos on the blog.
In the meantime, a video of the same incident, allegedly with audio, posted on YouTube. Concerned citizens believed this genuine video included the missing audio. Primeau Forensics investigated the YouTube video and here we offer an opinion as to the authenticity of this second version of the dash cam video that included audio.
During our investigation of the YouTube video titled ‘Is this the audio Chicago Police dash cam video of Laquan McDonald shooting?’, we discovered several inconsistencies that scientifically revealed the second YouTube video is a fake. Using time domain analysis, frequency domain analysis, and critical listening skills, we have outlined these anomalies and inconsistencies below.
In the image above, the spectrogram reading shows the cutoff frequency of the gunshots well above the cutoff frequency of the noise floor (background noise, radio chatter & siren). Shown below, a display of the difference in frequency content between the gunshots and background noise. Red vertical sections represent gunshots.
The audio’s cutoff frequency from the YouTube video titled ‘Is this the audio Chicago Police dash cam video of Laquan McDonald shooting?’ is roughly 16 kHz. Displayed below, the audio’s cutoff frequency from the YouTube video at 16 kHz.
Audio recorded evidence produced from law enforcement vehicles contains a cutoff frequency of 4 kHz. I examined the frequency analysis of the original video that lacks audio. The cutoff frequency analysis of the original audio portion is 4 kHz and displayed below:
Based on forensic testing and analysis, I can confidently say that an unknown party manufactured and added the audio portion in the second YouTube video after the fact.
The original video contains recorded audio content of cross-talk and engine noise (see above image). The audible noises within the original video recording have low amplitude. However, they are heard with a significant increase in volume. Because this digital recorder in the police car recorded audio track, I believe the recorder was functional. Due to the lack of officer dialogue and radio chatter, we believe the on-person lavalier microphone within the vehicle was muted, disconnected, or deactivated.
INAUTHENTIC AUDIO RESULTS
The gunshots and radio chatter heard throughout the YouTube video titled ‘Is this the audio Chicago Police dash cam video of Laquan McDonald shooting?’ are duplicated, equalized, and not authentic. I previously discussed the inconsistency between the cutoff frequency of the gunshots and the background noise. In addition, the audible fingerprint of the gunshots within the spectrogram has a distinct shape, size, and intensity that are consistent with duplication or repetition. The frequency decay of the gunshot, sound of the gunshot, as well as duration of the sound are almost identical. See image below for gunshot sounds.
The radio chatter sample at timecode 0:04.387 (MM:SS:MS) is an exact duplicate of 0:03.000 (MM:SS:MS). And so, the conversation being spoken is identical. The differnece is that the duplicate has been processed using equalization to deceive the listener into believing it is radio conversation.
The Laquan McDonald police video with audio is indeed fake.
Why is video authentication important? As a video forensic expert, I often find that videos submitted into litigation are not original as the person admitting has stated. Instead, they are copies that have been altered to only contain the events they want the trier of fact to see. From a forensic perspective, this is not fair because the original video will contain all the events as they actually occurred. Some of the events that were omitted have relevance to criminal or civil litigation.
Last week, I testified in court in a video authentication case. The report that I wrote for the case was admitted into evidence. My report revealed that a video had been altered and was not an original.
I testified that my report revealed the scientific findings and my conclusion that the video recording was altered and not an original. Both conclusions were scientific and if I conducted the same test 1000 times over, I would arrive with the same conclusions. If any other forensic expert were to conduct the testing that I had documented in my work product and report, they would arrive at the same conclusion as well.
Lately, I authenticate all forms of video. Store CCTV, cell phone video, and tablet video. We live in a video world! Anywhere you go out in public you are more than likely being video recorded. If you are riding a city bus, you are more than likely being video recorded. Some civilians have installed mobile CCTV systems in their cars just in case they need to defend themselves or catch a crime in progress.
The police originally installed cruiser video recording systems to first protect themselves and to also protect the citizens from prejudice. Cruiser video holds the police accountable by recording probable cause for traffic stops
Forensic experts have many tools to determine scientifically if a video is first, original and second if a video has been altered. It is especially difficult with digital video to determine how a video was edited if it does not purport to contain the information or events either litigator states that it should contain. This is where forensic investigation becomes the only way to determine the video evidence authenticity.
If you believe a video has been edited, here are a couple of things you can do personally to determine if your video may have been edited.
- First, determine the file format on your DVD or CD Disc. Insert the disc into your computer, left-click on the drive, and select open. Is the file format VOB or MP4, AVI, MOV? This format is actually the video container.
- Next, go back to the file folder, left-click to open, find the video, and right-click on the file. All the way at the drop-down menu is the word properties. Left-click to open and review the MAC information. Modified, accessed and created information will reveal dates. Does the disc/CD created day to read a date that the litigator who submitted the video stated the date created to be?
- The length of the video can also be a clue for your preliminary video authentication. Are there any phone records to compare to the length of the video? Does your memory of the series of events match the length of the video and video events?
Of course, there are many more steps a video forensic expert will take in order to determine if your video is genuine and authentic. Even if there is no audio on your video recording, the audio track can also reveal information about the authenticity of your video recording.
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