When looking into unresolved or cold cases, PPD may employ a number of tactics and methods.
Evidence and forensic materials are frequently reexamined using state-of-the-art equipment and scientific techniques. Forensic analysis can involve several methods, such as DNA testing and ballistics analysis. As part of their work, investigators may re-interview witnesses, speak with new individuals who may have information relating to the case, and pore over case files and prior investigations in search of new leads or ignored evidence.
In addition, local police may form partnerships with federal agencies like the FBI in order to pool resources and pool knowledge. They may also coordinate with regional media to increase exposure of the investigation and find fresh leads.
A number of police agencies have established "cold case units," staffed by investigators with expertise in reopening cold cases. Some agencies have specialized divisions whose job it is to reexamine closed cases for possible new leads and devise plans for reopening the investigations.
Involving and keeping the victims' loved ones informed during the investigation is another crucial tactic. Trust and collaboration between law enforcement and the families involved can be crucial in solving many cases, and this can assist foster that.
A police department's approach to a given case, the tools at its disposal, and the experience of its investigative officers will all influence the methods it employs. While inquiries into cold cases can be difficult and time-consuming, they can also give victims' families with closure and help individuals who have been wronged receive justice.