Diatoms constrain forensic burial timelines: case study with DB Cooper money

Area of Science:

• Forensic science
• Environmental science
• Microbiology

Background:

• Diatoms are microscopic algae found globally in aquatic environments.
• Seasonal diatom abundance varies, offering potential for temporal analysis.
• DB Cooper's recovered money was found far from the jump site, with an unknown immersion history.

Purpose of the Study:

• To determine if diatoms on recovered currency can indicate seasonal immersion.
• To apply diatom analysis to the DB Cooper case to constrain the timeline of the money's immersion.

Main Methods:

• Diatom species identification on a recovered DB Cooper bill.
• Comparison of the found diatom assemblage with a control bill submerged in the Columbia River during the crime's timeframe (November).

Main Results:

• Diatoms were identified on the recovered DB Cooper bill.
• The species composition indicated a summer bloom, not consistent with a November immersion.
• The money was likely immersed in water months after the hijacking.

Conclusions:

• Diatom analysis suggests the DB Cooper money was immersed in summer, not immediately after the November hijacking.
• This finding challenges existing theories about the case.
• Diatoms provide a viable forensic tool for establishing seasonal timelines of object immersion.