This September 2011 edition of The Police Chief contains eight primary articles dealing with lessons learned from the events of 9/11, and the use of forensics in policing. The first article, 10 Years after 9/11: Lessons Learned by the New York City Police Department examines changes made to the department following the events of 9/11. The second article, Handling Mass Fatalities: Advancements since 9/11 by the Office of the Chief Medical Examiner's World Trade Center Identification Unit examines how the office handles mass fatalities since the events of 9/11. The third article, Counter Criminal Continuum Policing in Springfield, Massachusetts: A Collaborative Effort between City and State Police to Reduce Gang Violence discusses the work of the Springfield, MA Police Department to reduce gang violence. The fourth article, Mobile Biometric Devices: What the Future Holds discusses the use of biometric devices by police departments. The fifth article, Shining a Forensic Light on the Warfight examines the use of forensic science tools by the U.S. Department of Defense. The sixth article, What Law Enforcement Needs to Know about Improvised Explosives, is a basic discussion of improvised explosive devices. The seventh article, The Arizona National Park Service Unit: Applying Advanced Investigative Science to Protecting the Nation's National Treasures, discusses the use of forensic tools by the National Park Service in Arizona. The eighth article, Challenges of Emerging Technology: Beyond the Technology Itself discusses how to effectively use new investigative technologies. Additional columns examine proposed changes to the constitution of the International Association of Chiefs of Police, legislative alerts, and technology updates.