A Hosed-Off Appliance, a Flooded Storage Unit, and a Positive Lab Result
You are the investigator for a fire in a detached 24 ft by 30 ft garage. On day 2 the homeowner's brother moved the suspected chest freezer to an open-sided carport and hosed it off because it smelled like burned plastic. You first saw the freezer on day 9, photographed it where it sat, placed it in a polyethylene tote with a lid, wrote your initials and the date on masking tape, and put it in a rented storage unit. Seven weeks later the unit flooded; the freezer now shows visible mold, and the original floor area has been repaved. Separately, you took a debris sample from the concrete slab at the doorway, sealed it in a polyethylene bag, and the laboratory reported light petroleum distillate present. The garage also held a lawn mower, two 5-gallon cans of gasoline, and a propane cylinder; the slab had an old oil stain that you photographed but did not sample.
1. Identify the chain-of-custody and preservation failures and state their likely effect on the case.
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Where custody broke: the freezer left the scene in the hands of a non-investigator and was washed with a hose. Both are destructive: washing can remove or relocate debris and residues, and the brother's handling breaks an unbroken custody link that no one documented.
The seven-day gap: there is no statement from the brother, no photograph of the item in its found position, and no record of who touched it or how it was stored. That gap is the single largest weakness in the file.
The label: initials plus a date on masking tape is inadequate. Masking tape fails in damp storage, the label does not identify the item by serial number, and it does not identify the collector's full name or agency.
The environment: a rented storage unit that floods is an uncontrolled storage location. Mold and water introduce contamination and change the item's condition.
Likely effect: this is generally a weight problem rather than automatic exclusion. The item may still be admitted, but any opinion that depends on its condition is weakened, and opposing counsel will use the gap to attack the whole investigation. The investigator's obligation is to disclose the gaps in the report, not to paper over them. A supplemental report documenting the break, with the timeline, protects both the case and the investigator.
2. Does the laboratory finding of light petroleum distillate prove an ignitable liquid was poured? Explain your reasoning.
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No, not as the file currently stands. Four reasons.
No substrate control. The same slab carried an old oil stain that you photographed but did not sample, and the garage contained mowers, gasoline cans, and a propane cylinder. Without a comparison sample from an unaffected area of the same slab, you cannot exclude the slab itself, or decades of incidental spills, as the source.
Container choice. Polyethylene bags are not the preferred container for ignitable liquid residue samples; metal cans or approved sampling bags are used because a plastic bag can allow loss of volatiles and is a possible artifact source. The container is now part of the question.
Reported class versus identification. Light petroleum distillate is a class, not a product identification. Gasoline, kerosene, parts cleaner, and various oil-based products can fall in or near that window. You need the chromatograms and the library match, and you need to see whether the pattern shows the aromatic profile and weathering of gasoline.
Significance limit. Even a confirmed ignitable liquid establishes that a combustible liquid was present. It does not establish that it was poured, by whom, or that it caused the fire. It has to correlate with an injury pattern such as a pour pattern, localized floor char, or protected areas.
Until those four points are resolved, the finding is a lead, not a conclusion.
3. What specific steps would you take now to strengthen or repair the evidence?
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Sampling. Take a substrate control from an unaffected area of the same slab, submit a blank can, and resubmit a fresh sample from an area of suspected pour if any remains accessible despite the repaving. Ask the laboratory for the raw chromatograms, the library match, the quality-control blanks, and a written statement of the method used.
The freezer. Obtain a signed statement from the brother with exact dates, what he did, and why. Photograph the freezer's data plate and serial number. Re-photograph it in its current state with a scale, and open a formal chain-of-custody record from day 9 forward with full names, dates, and signatures. If destructive examination is contemplated, give written notice to all parties so they may attend.
Scene and records. Pull the fire department report, dispatch and alarm logs, and any doorbell or neighbor video. Interview the homeowner about what was stored where and about the freezer's service history.
Reporting. Write a supplemental report that states the limitations of the freezer evidence and the sampling, so that the weaknesses are disclosed by you rather than extracted from you at deposition.