How do the men secure the crime scene? Throughout the play, what kind of clues do they seek?

The men really don't secure the crime scene. They believe that the stove was the only thing touched after the murder, but the home had been left unattended, so it would have been possible that things had been disturbed. Furthermore, everyone in the home during the investigation disturbed the crime scene by rifling through evidence in the kitchen and gathering Mrs. Wright's belongings in the bedroom.

The clues the men are looking for would be definite objects, they need the evidence necessary to convict Mrs. Wright.