Previously, he was the IITRI Chair Professor of Computer Science and the Director of the Information Retrieval Laboratory at the Illinois Institute of Technology.

His research interests focus on scalable information retrieval systems spanning search and retrieval and communications issues. His systems are deployed in commercial and governmental production environments worldwide. He frequently consults for industry and government and for key intellectual property litigation. In 2007, Springer Science and Business Media designated his co-authored book entitled "Information Retrieval: Algorithms and Heuristics" with the "Top Selling Title" award. He is the recipient of the 2007 ASIS&T Research in Information Science Award and a recipent of the 2008 IEEE Technical Achievement Award. He is a Fellow of the AAAS, ACM, and IEEE.