1.5 Link Analysis

1.5 Link Analysis

Effectively combining multiple sources of data can lead law enforcement investigators to discover patterns to help them be proactive in their investigations. Link analysis is a good start in mapping terrorist activity and criminal intelligence by visualizing associations between entities and events. Link analyses often involve seeing via a chart or a map the associations between suspects and locations, whether by physical contacts or communications in a network, through phone calls or financial transactions, or via the Internet and e-mail. Criminal investigators often use link analysis to begin to answer such questions as "who knew whom and when and where have they been in contact?"

Intelligence analysts and criminal investigators must often correlate enormous amounts of data about individuals in fraudulent, political, terrorist, narcotics, and other criminal organizations. A critical first step in the mining of this data is viewing it in terms of relationships between people and organizations under investigation. One of the first tasks in data mining and criminal detection involves the visualization of these associations, which commonly involves the use of link-analysis charts (Figure 1.1).

Figure 1.1: A link analysis can organize views of criminal associations.

Link-analysis technology has been used in the past to identify and track money-laundering transactions by the U.S. Department of the Treasury, Financial Crimes Enforcement Network (FinCEN). Link analysis often explores associations among large numbers of objects of different types. For example, an antiterrorist application might examine relationships among suspects, including their home addresses, hotels they stayed in, wire transfers they received and sent, truck or flight schools attended, and the telephone numbers that they called during a specified period. The ability of link analysis to represent relationships and associations among objects of different types has proven crucial in helping human investigators comprehend complex webs of evidence and draw conclusions that are not apparent from any single piece of information.