CRS, 24 May 07: Terrorist Precursor Crimes
Terrorist groups, regardless of ideological ilk, geographical location, or organizational structure, have certain basic needs in common: funding, security, operatives/support, propaganda, and means and/or appearance of force. In order to meet these needs, terrorists engage in a series of activities, some of which are legal, many of which are not. Terrorist precursor crimes, offenses committed to facilitate a particular attack or promote a terrorist campaign’s objectives, are thought to be often carried out far away from the primary theater of conflict associated with a terrorist group. Much of the precursor activity, especially with regard to crimes conducted for the purpose of fundraising, takes place in wealthy Western countries, including the United States. Precursor crimes, known and/or alleged, include various fraud schemes, petty crime, identity and immigration crimes, the counterfeit of goods, narcotics trade, and illegal weapons procurement, amongst others. The implications of domestically occurring terrorist precursor crimes on the current threat environment, and specifically the United State’s security posture, are not fully understood....
Along the same lines, here are a couple of good papers (2 years old) from NIJ:

Methods and Motives: Exploring Links Between Transnational Organized Crime & International Terrorism
The nexus with transnational organized crime is increasingly a focus for security planners in their analyses of terror groups. Their approach is best described by the phrase “methods, not motives.” While the motives of terrorists and organized criminals remain divergent most often, our research indicates this is not always the case. For that reason, this report argues that such a general approach has become too restrictive and can be misleading since the interaction between terrorism and organized crime is growing deeper and more complex all the time. In short, the lines of separation are no longer unequivocal.

The report analyzes the relationship between international organized crime and terrorism in a systematic way in order to highlight the shortcomings of the “methods, not motives” argument. In so doing, the report considers the factors that most closely correspond to crime-terror interaction and identifies those regions of developed and developing states most likely to foster such interactions. Likewise, the paper will suggest an evolutionary spectrum of crime-terror interactions that serves as a common basis for discussion of such often-used terms as “nexus.”

The centerpiece of the report is a groundbreaking methodology for analysts and investigators to overcome this growing complexity, identify crime-terror interactions more quickly and to assess their importance with confidence. The approach is derived from a standard intelligence analytical framework, and has already proven its utility in law enforcement investigations.

The report is the product of a recently concluded and peer-reviewed 18-month NIJ-sponsored research project, and includes empirical evidence drawn from numerous case studies developed in the course of the research program.
Crimes Committed by Terrorist Groups: Theory, Research, and Prevention
A decline in state-sponsored terrorism has caused many terrorist organizations to resort to criminal activity as an alternative means of support. This study examines terrorists’ involvement in a variety of crimes ranging from motor vehicle violations, immigration fraud, and manufacturing illegal firearms to counterfeiting, armed bank robbery, and smuggling weapons of mass destruction. Special attention is given to transnational organized crime. Crimes are analyzed through the routine activity perspective and social learning theory. These theories draw our attention to the opportunities to commit crime and the criminal skills necessary to turn opportunity into criminality. Through these lenses, the research appraises the "successes” and “failures” of terrorists’ engagement in crime.