PSI Case Example
On June 15th, 2008 Yolo County Sheriff’s Deputy Jose Antonio “Tony” Diaz was fatally shot after a high-speed pursuit of Defendant Marco Topete. Topete was found guilty in Yolo County Superior Court of First Degree Murder with Special Circumstances, and the Yolo County D.A.’s office is asking for the death penalty. On November 16, 2011, the jury sentenced Marco Topete to death for the Murder of Yolo County Sheriff’s Deputy Jose Antonio “Tony” Diaz. The verdict was read aloud in Department 3 before Judge Paul K. Richardson.
THE CHALLENGE
How to use the physical evidence captured at the scene of a fatal shooting to determine the shooter’s position relative to the victim, the victim’s positioning at key moments during the event and finally reconstruct the event with sufficient fidelity to the forensic evidence to successfully have the resulting 3-D animation admitted into trial.
THE SOLUTION
Perform bullet path analysis with sufficient accuracy to locate the shooter’s position through the use of a Leica Geosystems ScanStation 3-D laser scanner. Precision Simulations (PSI) deployed a Leica ScanStation at the request of the Yolo County District Attorney’s Office to assist the California Department of Justice with their investigation of the crime scene. 3-D laser scanning enabled PSI to precisely document the crime scene as well as the bullet-riddled patrol car in order to create a 3-D Working Model of the scene. Combining the 3-D Working Model with the audio and video captured from the camera system in the deputy’s patrol car enabled PSI forensic reconstructionist Craig Fries to devise several ground breaking new analyses that clearly showed the defendants claim of self-defense did not match the physical evidence.
THE CRIME
On June 15th, 2008 Yolo County Sheriff’s Deputy Jose Antonio “Tony” Diaz was fatally shot after a high-speed pursuit of Defendant Marco Topete. Topete was found guilty in Yolo County Superior Court of First Degree Murder with Special Circumstances. On November 16, 2011, the jury sentenced Marco Topete to death for the Murder of Yolo County Sheriff’s Deputy Jose Antonio “Tony” Diaz. The verdict was read aloud in Department 3 before Judge Paul K. Richardson.
Cartridge casings found at the scene indicated that the shooter had fired seventeen .223 caliber rounds from an AR-15 assault rifle at Deputy Diaz. One round pierced Deputy Diaz’ Kevlar vest fatally wounding him as he was watching over Topete’s young daughter who Topete abandoned in his vehicle after fleeing on foot.
PSI’s Chairman and Founder, Craig Fries, was the final witness for the prosecution. Mr Fries successful in getting an animated reconstruction of the event admitted into trial, along with a 150-slide PowerPoint presentation that clearly laid out the scientific foundation for the animation.
The multiple segment animation depicts the vehicular pursuit of the defendant and concludes with an animation of the shooter firing 17 rounds from the assault rifle at Deputy Diaz. In the animation, the Sheriff’s Deputy is standing near his patrol vehicle 70 feet away with his back turned as the shooter is shown taking aim from behind a nearby house, pulling the trigger 17 times.
ANALYSIS METHOD
PSI utilized an array of technologies in performing the reconstruction including 3-D Animation, 3-D Laser Scanning and Audio Frequency Analysis . Mr. Fries testified extensively on the methods used to determine the following:
- The location of the shooter behind the corner of house, 70 feet from Deputy Diaz
- The location and orientation of the AR-15’s muzzle when the 17 rounds were fired
- The location and orientation of the deputy’s patrol vehicle
- That Deputy Diaz had his back turned to the shooter at the time the shooter opened fire
- Which round in the sequence of 17 fired fatally wounded Deputy Diaz
PSI pioneered the use of 3-D Laser Scanning for Forensic Analysis in the late 1990’s and has been at the forefront of its use in accident and crime scene documentation and reconstruction analysis. PSI used the Leica GeoSystems ScanStation system which was praised by Mr. Fries for its accuracy and the internal dual-axis compensator which captures the leveled survey quality data required for sophisticated analysis and physics based crime scene reconstructions. It has the added benefit of being able to create visually compelling exhibits for a Jury’s ready comprehension.
LASER SCANNING BALLISTIC TRAJECTORY RODS EXTENDING FROM THE PATROL VEHICLE
PSI worked alongside a qualified firearms examiner from California Department of Justice’s Sacramento Crime Laboratory as they inserted ballistic trajectory rods into multiple bullet holes left in Deputy Diaz’ patrol vehicle. Using the ScanStation 3-D laser scanner to measure these rods guaranteed the most accurate data and analysis possible.
DOCUMENTING THE CRIME SCENE WITH THE 3-D LASER SCANNER
In addition to the deputy’s patrol vehicle, PSI used 3-D laser scanning to thoroughly and accurately document (map) the crime scene. An accurate 3-D model was critical to the success of the reconstruction, providing PSI with a virtual model of the scene and allowing very detailed analysis of the bullet trajectories within the scene. The ability of the ScanStation to capture fine detail at long range was key to being able to laser scan the subject house from the public roadway as the occupant was clearly agitated by the activity and would never have allowed access to the property.
3-D Laser scan of crime scene
3-D Laser scan of Deputy Diaz' patrol car with bullet trajectories
DoJ Evidence marker: Center of cartridge casings at crime scene
(Inset) Yolo County patrol car with ballistic trajectory rods inserted
DETERMINING SHOOTERS LOCATION BEHIND HOUSE FROM BALLISTIC TRAJECTORY ANALYSIS
Once the physical evidence had been meticulously documented with Laser Scanning, PSI developed a ground breaking new method of scientific analysis to determine the shooter’s position. This new method showed conclusively that Topete had taken a position behind the corner of a neighboring house, 70 feet behind Deputy Diaz.
Top Down View of 3-D Working Model of Crime scene with Vehicles and Ballistic Trajectories shown
Plus or Minus Five Degree Cones of Possibility
Perspective View of 3-D Working Model of Crime scene with Vehicles and Ballistic Trajectories shown
Overlap of 5 degree cones isolates Topete’s position in the “football shaped” area
Center of Overlap = Shooter’s most likely position
Shooter’s perspective View – Note the muzzle alignment with corner of house
Once the 3-D model of the patrol vehicle with the virtual ballistic trajectory rods extending from it was positioned within the 3-D crime scene, the location and orientation of the AR-15 was determined by using a revolutionary new method. Each bullet trajectory was assigned a +/- 5 degree cone of uncertainty which takes into account the error rate for this type of analysis. Mr. Fries then computed the common area where the six trajectories overlapped in 3-D. This common area was the only location where the shooter could have been to have left behind the pattern of ejected cartridge casings and match all six bullet trajectories.
BALLISTIC TRAJECTORY ANALYSIS OF FATAL ROUND
The final ballistic analysis involved determining the body position of Deputy Diaz when he received the fatal .223 round through the front of his Kevlar vest. This was a critical area to analyze given that early analysis of the evidence indicated that Deputy Diaz was standing with his back turned to Topete when the first shots were fired. This was corroborated by PSI’s analysis.
The Department of Justice’s Crime Lab issued a report stating that the round that went through Deputy Diaz vest came “from the Deputy’s right to left at a 55 degree angle…and from top to bottom at a 45 degree angle” .
PSI created a 3-D model based upon Deputy Diaz’ measurements then computed and illustrated 3-D ballistic trajectory that matched the 55 degree 45 degree angle specified in the DoJ report.
Deputy Diaz’ Kevlar vest with
location of fatal bullet entry
3-D model of Deputy Diaz with ballistic trajectory created from DoJ report data
The model of Deputy Diaz was inserted into the 3-D crime scene and moved around until the trajectory of the fatal round was aligned with the (now) known location of Topete. The result demonstrated that Deputy Diaz reacted to hearing the first shots by turning approximately 180 degrees and crouching near his patrol car, in keeping with his tactical training to “get small” when fired upon.
Location and body posture of Deputy Diaz at time fatal 8th round struck him in the chest
ANALYSIS OF AUDIO AND VIDEO FROM CAMERA MOUNTED IN DEPUTY'S PATROL CAR
PSI analyzed the video of the event as captured by the camera mounted inside Deputy Diaz’ patrol car. Although the shooting itself was not caught on tape, the audio of the event was, and this provided PSI with critical evidence needed to determine:
- That Deputy Diaz had his back turned to Topete when Topete started firing
- That Deputy Diaz was fatally struck by the eighth out of the17 rounds
- That Deputy Diaz spun around and crouched low to the ground in response to the shots fired at him resulting in his being struck in the chest
These critical facts put to rest any defense claim that the shooter fired in self-defense, as Deputy Diaz was proven to have had his back turned to Topete when Topete commenced firing. It also explained how the fatal round came to penetrate Deputy Diaz’ front side.
Frequency Analysis of the audio from patrol car camera system depicting the timing of each event
Timing data derived from Audio Frequency Analysis for each shot and Deputy Diaz’
exclamation of pain in response to eighth round striking him in chest
CLIENT COMMENT
“PSI’s excellent and sophisticated analysis proved conclusively that the defense version of events was invalid; their reconstruction presented these facts in the most compelling and persuasive manner possible, Mr. Fries’ trial testimony was among the most professional I have ever witnessed and was best received by the jury.” - Yolo County DA, Jeff Reisig
Clip from the 3-D Animation shown at trial. The multiple images show two views of the animation synchronized to the audio and video from the patrol car’s on-board camera system. This clip illustrates the event at the time the fatal Eighth round is fired by defendant Topete and strikes Deputy Diaz in the chest.