Thursday March 1 2018 Discussion and Complete Worksheet

Announcements Remediation for Quiz 12 ends tomorrow!

Assignment Summative or Formative # Date Issued Gone Missing Day Last Day Accepted QUIZ

Gunshot Residue (GSR) • GSR Sources: – Victim’s clothing – Target – Shooter’s hands.

Gunshot Residue (GSR) • Gunpowder Chemistry – Major detectable elements are: lead (Pb), barium

Griess Test • Tests for the presence of nitrates (partially burned or unburned gunpowder)

Results of GSR Hand Test • Negative results may be caused by: – Washing

GSR on the hand of a suicide victim, proving he was holding the weapon

SERIAL NUMBER RESTORATION – When a serial number is stamped into a gun, the

Before & After – Historically, serial numbers are successfully restored 63% of the time

FIREARMS EVIDENCE COLLECTION • Make sure the weapon is unloaded! • REVOLVERS – Indicate

FIREARMS EVIDENCE COLLECTION • AMMUNITION – Write on base or nose – Package in

FIREARMS EVIDENCE COLLECTION • CLOTHING – Protect & preserve any residue – Air dry

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Thursday March 1, 2018 (Discussion and Complete Worksheet - Firearms)

The Daily CSI Thursday, 3/1/18 ? ?

Announcements Remediation for Quiz 12 ends tomorrow!

Assignment Summative or Formative # Date Issued Gone Missing Day Last Day Accepted QUIZ 12 S 3 2/26 Friday N/A Hold for e. Research Paper WS – Firearms F 11 2/27

Gun Shot Residue (GSR)

Gunshot Residue (GSR) • GSR Sources: – Victim’s clothing – Target – Shooter’s hands.

Gunshot Residue (GSR) • Gunpowder Chemistry – Major detectable elements are: lead (Pb), barium (Ba) & antimony (Sb) – Virtually all cartridge cases are made of brass (copper & zinc)

Griess Test • Tests for the presence of nitrates (partially burned or unburned gunpowder) • Swab of shooter’s hand • Must produce a pattern for a distance determination

Results of GSR Hand Test • Negative results may be caused by: – Washing the hands – Shooter may have been wearing gloves – Lead free ammunition • A rifle or shotgun may not deposit GSR on hands

GSR on the hand of a suicide victim, proving he was holding the weapon when it was fired.

SERIAL NUMBER RESTORATION – When a serial number is stamped into a gun, the metal underneath the number is compressed & hardened. – If the number is filed-off, the hardened area may still be present. – By using an acid solution the metal can be slowly eaten away. • In this process the softer metal will be eaten away first and the number may reappear.

Before & After – Historically, serial numbers are successfully restored 63% of the time on steel & 54% of the time for aluminum or zinc.

FIREARMS EVIDENCE COLLECTION • Make sure the weapon is unloaded! • REVOLVERS – Indicate location of fired & unfired ammunition • AUTOMATICS – Check magazine for number of rounds – Fingerprint magazine • Place ID tag on trigger guard

FIREARMS EVIDENCE COLLECTION • AMMUNITION – Write on base or nose – Package in pill box or envelope – Wrap in tissue to protect

FIREARMS EVIDENCE COLLECTION • CLOTHING – Protect & preserve any residue – Air dry if wet – Package separately in paper bags • Establish CHAIN OF CUSTODY

Complete Worksheet Firearms