Identity resolution is central to fighting against crime and terrorist activities in various ways. Current information systems and technologies deployed in law enforcement agencies are neither adequate nor effective for identity resolution. In this research we conducted a case study in a local police department on problems that produce difficulties in retrieving identity information. We found that more than half (55.5%) of the suspects had either a deceptive or an erroneous counterpart existing in the police system. About 30% of the suspects had used a false identity (i.e., intentional deception), while 42% had records alike due to various types of unintentional errors. We built a taxonomy of identity problems based on our findings.