(a) The department shall immediately initiate an investigation after the receipt of any report. The department shall direct and conduct all investigations; however, it may delegate the conduct of investigations to local police authorities or other appropriate agencies. If such delegation occurs, the agency to which authority has been delegated must report the results of its investigation to the department immediately upon completion.

(b) The investigation shall determine the nature, cause, and extent of the reported abuse or exploitation, an assessment of the current condition of the resident, and an assessment of needed action and services. Where appropriate, the investigation shall include a prompt visit to the resident.

(c) The investigating agency shall collect and preserve all evidence relating to the suspected abuse or exploitation.

(d) All state, county, and municipal law enforcement agencies, employees of long-term care facilities, and other appropriate persons shall cooperate with the department or investigating agency in the administration of this article.