Iowa State University
Computer and Network Forensics
CprE 592-YG
October 23, 2003
By
Sandra J. Stoltenow, Criminalist Supervisor
Iowa DCI Lab

• Document chain-of-custody
• List and describe items examined
• Describe methods of examination, if appropriate
• State results of examination
• State significance of results
• Special interpretations
• Disposition of evidence

• Can be delegated to submitter
– Submission form
– Receipt form
May need to be corrected or supplemented

Preparation
Instrumentation
Destructive or nondestructive
Suitability to be re-examined by another expert

• Use layman’s terms if at all possible
• Graphics or tables are helpful
• Be clear and concise
• Explain limitations

• Exhibit A and B were identical and likely have a common source
• Because the genetic profile of the suspect does not match the semen on the victim’s vaginal swab, this suspect is eliminated as the semen donor.
• The suspect was in contact with the victim by e-mail.

• Assuming a 40% yield, the precursors found in the defendant’s apartment could have made 15 grams of pure methamphetamine.
• Seminal fluid from an additional, unknown male was identified on the vaginal swab.

The Macintosh Computer (serial number
45689) is being returned under separate cover by Federal Express number 1234.
The hard drives labeled Exhibits 14-20 are being forwarded to ABC Data Recovery at the request of the plaintiff.
The server described above is available to be returned to your office at your convenience.

• Notify the submitter of the progress of the analysis
• Can stand alone

“In science the credit goes to the man who convinces the world, not the man to whom the idea first occurs.”
Sir Francis Drake
“Science advances toward truth though never arriving at certainty.”
Unknown

• The American Adversary System
• Terms
• Expert Testimony
• Frye v. United States
• Daubert v. Merrell Dow Pharmaceuticals inc.
• Kumho Tire Co. v. Carmichael

• Cases are heard by a neutral and passive decision maker
• Setting is highly structured
• Evidence is usually presented by lay witnesses who must testify based on personal knowledge (expert witnesses are exception).

• Minutes of testimony
• Subpoena
• Interogatory
• Deposition
• Duces Tecum
• Opening Statement
• Direct Exam
• Voir dire
• Cross Exam
• Re-direct, Re-cross, etc.
• Sequestered

• Sustained
• Over ruled
• Multifaceted questions
• Chain of Custody

• Only expert witnesses are allowed to testify to matters they did not directly perceive.
• The subject must be outside the general knowledge of lay jurors.
• It must involve “scientific, technical, or specialized knowledge” such that it would assist the jury to have an expert explain.
• The witness must have sufficient training and experience.

• Excluded testimony about a primitive polygraph
• Science can be used in the courtroom only if the procedure is “sufficiently established to have gained general acceptance in the particular field in which it belongs.”
• When is Frye applicable?
• What is meant by general acceptance?
• Which scientific community?
• How do you accommodate new advances?

• No mention of Frye
• Meant to reduce formality
• Junk science flourished
• Iowa is a Federal Rules of Evidence State

• Rejects the Frye for Federal Courts
• Trial judge must serve as gatekeeper to screen unreliable evidence.

• Extended the trail judge’s gate keeping role to all expert testimony
• Distinction between scientific and technical or specialized knowledge is not clear.
• Expert, whether scientific or not, must
“employ in the courtroom the same level of intellectual rigor that characterized the practice of an expert in the relevant field.”

• The scientific community Frye
• The jury – Federal Rules of Evidence
• Trial judge – Daubert, Joiner, Kumho
• The appellate courts – Goeb v. Tharaldson

• Provide a resume
• Require a pre-trial conference
• Dress the part
• Prepare visual aids
• Practice what you can

• Through short training lay jurors can improve scientific problem solving ability
• Jurors will use past experiences to assess evidence to test which story is most believable
• Only if Jurors lose motivation or ability to fit evidence into story will they resort to peripheral cues.

• Too complicated
• Not trained by your testimony
• Too much detail
• Too much jargon

• Talk to jurors. Give them eye contact
• Teach them to evaluate the evidence
• Help the jurors understand that the evidence fits the story

• Black robed, failed scientists?
• Learning the job as they go.
• Previous difficulty with science and technology
• Unbiased?

• Listen to the question
• Pause before answering
• Answer the question
• If you don’t know, say so

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Anonymous
1993 The Dead Rise Again in the Courtroom. The National Law Journal, June 21, 1993.
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1999 How to Excel During Depositions: Techniques for Experts that Work. SEAK Incorporated, Falmouth, MA.
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2002 Expert Evidence.
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Becker, Ronald F.
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