Tomas Guillen is a Professor in the Communication Department. Besides teaching journalism courses, he offers an interdisciplinary course titled: Cops, Crooks, Justice & The Media. Occasionally, he is asked to discuss law enforcement and criminal justice issues on national broadcast news programs. Before joining Seattle University, he worked as a journalist for twenty years at several daily newspapers, including The Seattle Times, Omaha World-Herald, and the Tucson Citizen. As a journalist, he specialized in investigative reporting and criminal justice issues.

In 1990 Guillen co-authored The Search for the Green River Killer and in 1995 he authored the book Toxic Love. In 2006 Prentice Hall published his text book, Serial Killers: Issues Explored Through the Green River Murders. An interactive DVD with the killer’s confession complements the book. The Search for the Green River Killer became a N.Y. Times National Bestseller.