I have had more than 35 years experience in scanning electron microscopy (SEM)/elemental analysis (EDS), the instrumentation utilized for the analysis of gunshot residue (GSR) in shooting cases. My expertise with GSR is more than 20 years. I have also had 15 years training and experience in bloodstain and crime scene analysis.
The high profile case of People v. Phil Spector has received extensive coverage by CourtTV and other media. An important part of the circumstantial evidence presented by the prosecution involved GSR. Unfortunately, poor training of one of the experts severely handicapped the prosecution in this important aspect of this shooting.
Two experts presented their findings in court: Christine Pinto and Steve Dowell. The broadcast by CourtTV of the testimony of these individuals was abbreviated. Although I may have missed critical testimony in the presentation and interpretation of the gunshot residue evidence, I believe that my observations regarding the GSR evidence accurately reflect the prosecution’s presentation.
My focus is the work and testimony of Pinto, a criminalist with whom I have had no previous encounter. Her part of the case concerned the GSR samples from Spector’s hands. Even though Pinto had access to Spector’s clothing, specifically the white sports jacket that Spector was wearing at the time of the shooting, she did not sample that jacket for GSR. Unfortunately, she has maintained the irrational assumption that fabric cannot be reliably sampled. The same assumption was also proffered by Los Angeles Police criminalist, Colin Yamauchi, in the Robert Blake criminal trial (meixatech.com/blake.pdf). Apparently, the fear for fabric sampling is the long-term persistence of GSR on garments and one cannot establish that the shooting at issue deposited any GSR discovered on the fabric. These criminalists do not consider the probability of a recently washed or dry cleaned article of clothing from articles such as causal and work jackets which rarely get cleaned. Gunshot residue deposited on hands, however, is generally thought to be more reliable for determining if the person sampled was recently exposed to GSR. There are serious problems associated with hand sampling for GSR:
1. Time of sampling after shooting. It is accepted that due to the normal activities of a shooter that there is an exponential loss of GSR from his hands from the time of the shooting. The maximum time for sampling the hands of a shooter is accepted for most GSR experts to be three to four hours from the time of the shooting, although a few believe that sampling can be as much as eight hours and still generate reliable results.
2. Hand wiping and washing prior to sampling. Not factored into the above time estimates, is that the shooter may wash or actively cloth wipe his hands soon after a shooting and remove most, if not all GSR deposited on his hands. It is apparent that Spector washed his hands during the interval from the time of the shooting to when the police arrived 40 minutes later.
3. Skin epithelial cells and oils. Skin debris (exfoliated cells and skin oils) on the GSR sampler have been shown to obscure particles (meixatech.com/SKINDEBRISandGSRSAMPLING1.pdf and meixatech.com/SKINDEBRISII.pdf). Individuals vary in the amount of exfoliation of skill cells as well as the amount of oils on skin. Gunshot residue may be present on a hand, but obscured by this organic debris.
4. Police environment contamination. It has been reported in the forensic literature that police cars and stations are contaminated with GSR. Precautions must be made to isolate a suspected shooter from GSR contamination in the police environment.
It is apparent that fabric sampling may have more potential for providing inculpatory evidence in some cases than bare hand sampling. Spector’s white sports jacket should have been sampled for GSR. I have worked cases where the sampling of fabric (and other inanimate objects) for GSR was a key aspect of the case. Not finding GSR on clothing worn by the defendant at the time of the shooting is often exculpatory.
The firearm in this shooting was a .38 revolver. Revolvers usually emit much more GSR than semiautomatic pistols due to the escape of gases and GSR from the revolver’s cylinder gap. A shooter has more of a probability to become contaminated with GSR when shooting a revolver rather than a pistol.
Spector was wearing a white jacket that appeared quite clean save for blood spatter. I think it is safe to assume that the jacket was not involved in a previous exposure to GSR. If indeed Spector fired the shot, then his right sleeve (assuming he is right-handed) would have received the greatest concentration of GSR. Gunshot residue deposition would decline the farther away from the cylinder gap and would be distinguished from passively deposited air-borne GSR (a control sample from an area not exposed to the direct deposition of GSR). For sampling, what would be needed is a stratified quantitative sampling routine. Considering the evidence that Spector washed his hands from the time of the shooting to his hands being sampled, a fabric sampling would potentially produce more reliable evidence that he did/did not have his hand in close proximity to the revolver when it fired.
Contact or near contact gunshots to heads have been shown to produce a two-phase blowback (Burnett, 1991, Journal of Forensic Science 36:1745-1752 and meixatech.com/COLSABOWHOMICIDE.pdf), when there is no exit wound. In the former citation, I did comment on the second (“phase 2” — see latter citation) blowback phenomenon in the shooting experiments with pigs where I state, “A white mist appeared to emanate from the wound for the contact and near contact shots, which formed a cloud about 1 m in diameter several seconds after the shot.” In that 1991 experiment, it was also observed that the “exhalation” of the injected gases into the head was not expelled immediately after the shot, but appeared to be delayed for approximately one second and then the escaping gases through the bullet hole in the head produced the cloud. I did not realize the importance of this observation at the time of the 1991 work, but it became a key observation for the interpretation of the blood evidence in the Colonel Sabow homicide (latter citation). Assuming that Spector did fire the shot, he could have stepped back and shifted his arm position within that one second after the shot and then receive the back spatter from the bloody blowback. The fine blood spatter observed on his jacket appears to be consistent with this scenario. If his hand was on the revolver when it was discharged, his jacket sleeve near that hand could not have avoided GSR from the revolver’s cylinder gap.