Although dominant effects of tasks on individuals' information-seeking behavior is accepted by many scholars, a limited number of studies has been conducted to reveal the nature of the relationship between tasks and information-seeking behavior. In their studies, some earlier researchers categorized tasks according to their complexity while others did the same according to the specifications of tasks. Two of the groundbreaking researchers in this area are Katriina Byström and Kalervo Järvelin who contributed to the understanding of the relationship between task complexity and information-seeking behavior. However, their findings also need empirical support for theory growth. In response to this need, this study attempts to test Byström and Järvelin's findings through a research using different research methods and applied in a police work environment. Other than providing empirical support for theory growth, this research is also expected to contribute to the understudied area of police information-seeking behavior. Both qualitative and quantitative data were collected from the participants who came from traffic, homicide, and anti-terrorism divisions of Ankara, Eskisehir, and Kirikkale Police Departments in Turkey. The participants identified terrorism cases as the most complex cases to solve, followed by homicide and traffic accident cases. Differences in the information-seeking behavior of three groups of police officers were examined through qualitative and quantitative data analysis. Oneway ANOVA technique and post hoc comparisons were used to analyze the quantitative data. In addition to shedding light on information-seeking behavior of police officers investigating related cases in Turkey, the results provided support for Byström and Järvelin's findings. For instance, the officers investigating more complex tasks used significantly more information sources than the others, while the use of external information sources was significantly higher in more complex cases.