Final answer:
A forensic entomologist might be called to investigate insect activity related to a death, but not for cases like flea infestations found at a dog pound, as they do not involve estimating the time or location of death.
Step-by-step explanation:
A forensic entomologist specializes in the study of insects and their development stages, particularly as they relate to criminal investigations. In the context of death investigations, forensic entomologists are primarily concerned with the study of insect colonization patterns on deceased individuals to estimate the time of death and possibly the location of the death. Therefore, amongst the options provided, a forensic entomologist might be called to help with any one of the following cases except 'flea infestations found at a dog pound'. This scenario does not involve the investigation of a death where determining the time or location of death is necessary, which is the typical purview of forensic entomology.