IGG software: the investigative genetic genealogy tools, explained

What IGG software is

Investigative genetic genealogy (IGG), also called forensic genetic genealogy (FGG), identifies an unknown person from the people who share DNA with them. A DNA profile is compared against a genealogy database, the closest matches are researched back to their ancestors, and the family trees of several matches are built until they meet. The descendants of those shared ancestors are then traced forward until one person fits the DNA, the age and the place.

The same method solves unknown parentage cases (adoptees, donor-conceived people, unexpected parentage) and law enforcement cases: unidentified human remains, violent crime and cold cases.

IGG software is the set of tools used along the way. Some find the matches, some interpret the amount of shared DNA, and some hold the research itself. Most IGG teams use several.

The tools, by stage of a case

1. DNA match databases

Where the matches come from. GEDmatch PRO (run by QIAGEN) is the law enforcement portal to GEDmatch, and FamilyTreeDNA also accepts law enforcement uploads. Consumer companies such as Ancestry, 23andMe and MyHeritage hold far more testers and are central to unknown parentage work, but their terms rule out most law enforcement use.

2. Relationship and placement calculators

Turn shared centimorgans (cM) into likely relationships. The Shared cM Project by Blaine Bettinger is the standard reference for cM ranges. DNA Painter offers the Shared cM tool and What Are the Odds? (WATO), which scores where an unknown person most likely sits in a tree. BanyanDNA runs placement calculations on complex trees with half relationships and pedigree collapse.

3. Clustering and automated trees

Sort a long match list into family groups. Genetic Affairs makes AutoCluster, AutoTree, AutoPedigree and AutoKinship, which group matches that match each other and reconstruct likely trees from their data. Manual methods such as the Leeds method do the same job in a spreadsheet.

4. Tree-building and case workspaces

Where most of the hours in a case go: building a tree for each match, finding where those trees meet, tracing descendants and documenting every source. Consumer tree builders and desktop genealogy programs are made for one family's tree. CanopyLink is built for this IGG stage: many trees per case, linked at their shared ancestors, with the case file and team alongside.

5. Records and research

The genealogy itself: census and vital records, newspapers, obituaries, city directories and public records, from FamilySearch, Ancestry, Newspapers.com, Find a Grave and others.

IGG tools side by side

The question each tool answers best. Features change often, so check each maker's site for what is current.

Where CanopyLink fits

CanopyLink is a web-based IGG tool developed with investigative genetic genealogists. Each case is a project, and each DNA match gets a tree of their own. You link the trees where they share ancestors, and CanopyLink shows where the matches' lines meet.

• Linked match treesOne tree per match, joined at shared ancestors, with merge and unmerge.
• Match LinesColor each match's line up the tree and see shared ancestors marked.
• Project MapBirths, deaths and sources on one map, colored by match line.
• Match list importCSVs from GEDmatch, MyHeritage, FTDNA and 23andMe become trees with their cM.
• Candidate reportsPDFs drawn around a candidate, with matches numbered, not named.
• Built for sensitive casesPrivate by default, team roles, names and notes encrypted at rest.

See every feature, or walk through an unknown parentage case step by step.

Choosing IGG tools

For law enforcement work, start from what the case allows: which databases may be searched under their terms and the U.S. Department of Justice interim policy, and how the research must be documented. Choose a workspace that keeps case data private, controls who on the team can see it, and produces reports that can be shared without exposing match names.

For unknown parentage, test where the most matches are, then pair a calculator such as WATO with a workspace where you can build several match trees and see where they meet.

For teams and teaching programs, look for shared projects with roles, so researchers and students work in one case without sharing a login.

Questions about IGG software