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Dzhokhar Tsarnaev— Case Archive
evidenceevidencephysical2015 Federal TrialVacuum filters Q1283 through Q1291, vent filter Q1292, and swabs Q1293David McCollam identified Q1283 through Q1291 as vacuum filters, Q1292 as a vent filter, and Q1293 as swabs, with a dormitory collection location supplied to the laboratory rather than known firsthand. He reported that the vacuum filters screened negative for the typical explosive-residue traces tested, not that the room was free of all explosive-related activity.
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Physical Evidence

Vacuum filters Q1283 through Q1291, vent filter Q1292, and swabs Q1293

David McCollam identified Q1283 through Q1291 as vacuum filters, Q1292 as a vent filter, and Q1293 as swabs, with a dormitory collection location supplied to the laboratory rather than known firsthand. He reported that the vacuum filters screened negative for the typical explosive-residue traces tested, not that the room was free of all explosive-related activity.

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Watkins used the negative vacuum-filter screening results to contrast dormitory samples with positive findings on other objects, without establishing a broader conclusion about activities in the room.

Trial Record (1)