Hale and Mrs. Peters would have realized that they, for the most part, could be a great help in this case. Graspell wrote the story in 1917, so setting dated back at least that far, perhaps further. Alhough the female gender had come quite a long way up to that point, with the whole Susie the Riveter era coming into effect and women starting to fend for themselves, there were still a large majority of men and even women who still considered the female's role less significant than the male role.
Next, the evidence that Mrs. Hale and Mrs. Peters uncovered is the most important proof, and shouldn't be hidden due to them feeling sorry for Minnie.
Mrs. Hale felt much pity for Minnie Foster, because she used to have much town popularity. For example Mrs. Peters stated "The law has got to punish crime. Mrs. Hale," and Mrs. Hale replies, "I wish you"d seen Minnie Foster."(Glaspell Pg. 74) Mrs. Hale didn't care whether or not she did murder her husband, but Mrs. Peters, being the sheriff's wife, probably felt like she had more responsibility and authority, and had second thoughts about concealing the bird from the men. At this point in the story both the women unquestionably knew that the once happy Minnie Foster turned sour and hung her annoying husband. They discovered a bird cage that had been abused and tampered with that certainly stirred Mrs. Hale and Mrs. Peters o thinking why had Minnie gotten so destructive with the bird cage. Mrs. Hale knew that there was a man that came through town a while back selling canaries, but since then no birds of any sort were being sold in there town. At this point in time the ladies were curious to find out what had happened to the missing bird. Then when the ladies were gathering up Minnie's items that she had requested to have brought to her down at the police station, they were rummaging through her sewing belongings thinking she might enjoy sewing why she is detained; they found the dead bird that belonged to the cage.