Chapter 24: Forensic DNA Databases: Tools for Crime Investigation

Forensic DNA databases

Forensic DNA databases

These are networks for exchanging information among law enforcement agencies to assist in solving crimes.

National DNA Database (NDNAD)

The world’s first DNA database established in United Kingdom.

Combined DNA Index System (CODIS)

Established in the USA three years after NDNAS was established.

Local DNA Index System (LDIS)

It is maintained at crime laboratories operated by police departments, sheriff’s offices, and local agencies.

Indexes

The DNA profiles entered in CODIS are organized into categories.

Convicted Offender Index

It contains DNA profiles of individuals convicted of crimes.

Arrestee Index

It contains DNA profiles of arrested individuals. It varies in SDIS databases based on each state’s law permitting the collection of DNA samples from arrestees.

Forensic Index

It contains DNA profile derived from crime scene evidence.

National Missing Person DNA Database (NMPDD) Program

Established by the FBI for the identification of missing and unidentified persons at the national level.

Missing Person Index

Contains DNA profiles voluntarily contributed from relatives. This index may also store patrilineal or matrilineal DNA profiles from the relative such as a biological father, mother, or child of the missing person to assist investigations.

Unidentified Human Remains Index

Contain DNA profiles from missing persons and unidentified human remains.

Rapid DNA Program Office

Established by FBI for the purpose of developing rapid DNA technology.

Rapid DNA technology

A fully automated process of performing STR analysis within 1–2 h to generate a CODIS core STR profile from a reference sample such as a buccal swab.

Rapid DNA Index System (RDIS)

The proposed index of NDIS. It shall be an integrated system capable of applying rapid DNA technology and carrying out database searches from police custody or booking units by trained police officers.

Rapid DNA instruments

Are portable, compact instruments designed to be deployed into field testing. These instruments are fully automated for processing reference samples in order to generate a DNA profile in less than 2 h.

NMPDD

Y-STR and mtDNA profiles may only be searched within ______-related indexes.

restriction fragment length polymorphism (RFLP)

The CODIS software no longer supports searches of DNA profiles generated by _________ analysis.

Hit

A match made from the information provided by comparing a target DNA profile against the DNA profiles contained in the database.

Offender Hit

Provides the identity of a potential suspect of a crime.

Forensic Hit

Reveals the linkage between two or more crime scenes.

Case-to-Offender Searches

Matches of profiles from the Forensic Index and the Offender Index reveal the identities of perpetrators of crimes.

Case-to-Case Searches

A target DNA profile from a crime scene is also searched against the profiles stored in the Forensic Index of the database.

Case-to-Case Searches

Matches of profiles among the target profile and the profile in the Forensic Index can link separate crime scenes and aid in identifying serial offenders.

Investigation-aided cases

are those assisted by CODIS hits, including case-to-case matches as well as case-to-offender matches.

high-stringency match

A ______ requires an exact match in which all alleles are matched at each locus between the target and candidate profiles.

moderate-stringency match

A __________is a candidate match “between two single source profiles having at each locus all of the alleles of one sample represented in the other sample.”

low-stringency search

In a ________, both mismatches and allelic dropouts are allowed.

Familial Search

A new method of applying database in criminal investigations; which is based on the assumption that close relatives share more alleles of DNA profiles than unrelated individuals.

Identity-by-state (IBS)

A method that compares the number of shared alleles and loci between a target forensic profile and the offender profiles in a database but does not take into account allele frequencies.

Kinship Index (KI)

A method that evaluates the familial match by comparing the probability that two DNA profiles are from related individuals to the probability that they are unrelated.