criminal investigations

You are a detective called to the scene of a homicide in an apartment building. The deceased is a young male who has been stabbed numerous times. The roommate of the deceased man is present in the room, his shirt is covered with blood, and there is a knife on the floor. Uniformed officers are guarding the doors and the roommate. There are four (4) important actions you must take; discuss each of these fully including how the actions should be taken, their importance, and consequences of not taking the actions