How Scan Data can Help Corroborate or Challenge Claims of Self-Defense
When prosecuting a homicide, it’s not unusual for defendants to claim self-defense. However, it can be difficult to determine whether those assertions are true. In these cases, 3D laser scan data can give detectives valuable insight. Criminalist Steven Alexander, of the Cincinnati Police Department’s Homicide Unit and Criminalistics Squad, recounts one case in which their Leica ScanStation and supporting software helped corroborate a robbery victim’s claim of self-defense.
The victim’s account
The incident involved an attempted robbery in which one of two assailants was shot and killed. Alexander was deployed to document the scene. “We had a man who was getting robbed by two other men,” Alexander explained. “We didn’t know these specifics at the time, but the man getting robbed ended up shooting back and killing one of the robbers.
“When the robbery victim came into the interview, he told the detectives, ‘Yes, I shot the guy, but I was just defending myself. I was actually on the ground. They are were coming at me, and I was shooting at them from the ground.’ We get that a lot, and trying to prove that or show that can be very difficult.”
The scan data’s account
To determine the veracity of the shooter’s claim, Alexander examined the scan data, including that of the trajectory rods he had placed in the bullet penetrations of a nearby building.
The data gave the detectives precisely the analysis they needed. “It was very clear that these shots certainly did come from near ground level at an upward angle very much like he described,” Alexander said. “He was very close to a building. With the angle that the shots came from, he couldn’t have been standing unless he had put his hand down by his knee and shot upwards. Just because of the distance to the house, there was no way he could of been standing. He had to have been on the ground like he was saying.”
The jury’s verdict
When the case went to trial, Alexander testified and presented screenshots created within Leica’s Cyclone point cloud processing software. “We essentially had to show that, yes, this man was shooting back, but he was on the ground and trying to defend himself from the ground. It’s not as if he was the primary aggressor,” Alexander said. “We were able to show that with the laser scanned trajectory rods.”
In the end, the surviving robber was charged in the death of his partner. “The scan data scientifically validated the victim’s story,” Alexander said. “It allowed us to get a better idea of who really was initially the victim versus the suspect, who ended up dying and becoming the victim of a homicide, even though it really was self-defense.”