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Law Enforcement
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Forensic video analysis yields important evidence
Feb 3, 2006
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by Scott T. De Broux
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I was working a homicide case where officers recovered surveillance video from a convenience store. Also, there were five mobile videotapes from responding squad cars and audio tapes of communications between officers, dispatchers, and 911 calls.
The case essentially involved two separate groups of individuals who arrived at the store shortly after a bar closed. There was a very minor verbal exchange between the suspect and the victim while they were in the store together.Once outside, the suspect again confronted the victim. He then pulled out a 9mm semi-automatic pistol and shot the victim one time in the chest. The victim died nearly instantly.
The suspect fled the scene on foot but was apprehended a couple of blocks away. A police canine located a loaded 9mm semi-automatic pistol wrapped in a black cap about 50 feet from where the suspect was taken into custody. Another group of individuals who were with the suspect were apprehended nearby.
No Witnesses
The challenging part of this investigation was that no witness saw the gun in the shooter's hand or actually saw him shoot the victim. Plus, the actual shooting wasn't captured on tape. Witnesses did report seeing the suspect wearing a hat similar to the hat found wrapped around the gun.
Forensic examination of the evidence yielded some good results. A bullet was recovered from the victim during autopsy. Because the bullet didn't pass through the victim's body, we had to rely on witness statements to place the victim and the shooter, as we had no definite trajectory path.
Examination of the hat produced a DNA profile that matched the suspect to about 1 in 10,000,000 probability. This was a great piece of evidence -- but for several reasons the DNA results were excluded from the trial.
The bottom line is this case came down to who had the opportunity to actually shoot the victim from within the range indicated by the firearm's examiner. Early on I was working on the surveillance video and an investigator asked, "Why are you spending so much time on that? It doesn't show anything but what happened before the shooting." Turned out it showed plenty.
During analysis of all the video and audio evidence, I discovered that dispatch had two different times, each mobile videotape had a different time stamp, and the surveillance videotape had two time stamps (one from the VCR and a second from the multiplexer). By analyzing all of these tapes, I was able to find common events on each and established a time conversion chart so the tapes could be synchronized. Once this was done, I was able to establish a timeline of events leading up to the shooting and the apprehension of all the suspects.
Timelines And Fashion Statements.
At trial, the defense attempted to convince the jury it took hours to occur. The timeline I presented helped show the jury the truth. The amount of time the defendant and suspect were in the store together to the time of the shooting was less than five minutes.
From the videotape, I was able to determine what each of the individuals purchased while in the store. I subsequently located these items in various locations in vehicles, etc., which told the jury something about where the individuals were or went after they left the store. This became important because we were able to corroborate some witness statements about where they were at the time of the shooting by where these items were found.
The surveillance videotape was a conventional analog multiplexed time-lapse tape. I demultiplexed the tape and was able to correct it to play in real time. I had to explain how this process works to the jury (and why the motion they saw on the real-time tape was jerky). It also became important to illustrate to the jury that the videotape is a series of still images, and there are periods of time between actual images (refreshes) where no information is captured.
Comparison of clothing was a huge issue with the absence of DNA evidence. We were able to show the suspect on the videotape in the store and outside just prior to the shooting wearing a hat with the same class characteristics as the hat recovered with the gun. Also, the suspect was wearing a shirt with very unique lettering on the front. Comparison of the suspect wearing the shirt on the videotape with the shirt seized from the suspect when he was taken into custody was important.
The sequence outside the store was very significant. Most of the important details were located in the underscan area of the videotape. I had to explain this to the jury and tell them how we analyze a videotape so we can see all the information including that in the underscan area.
Without the knowledge I gained during LEVA's "Basic Forensic Video Analysis and the Law" course in May 2005, I could not have successfully presented this case. The LEVA training was honestly the most challenging course I have taken as a law enforcement officer, but the knowledge I gained helped me appear more confident and credible to the jury. By the way, the suspect was convicted and is facing life imprisonment.
Scott T. De Broux is an identification officer for the Appleton Police Department in Appleton, WI.
MORE INFO
LEVA www.leva.org
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