particle feathers. >> reporter: thompson peered through his microscope, studying bloody strands of hair found clutched in kathleen peterson's hand. tangled in the hair were not one but two minute bird feathers. a surprise he says to the detectives and an assistant da watching in the room. >> i think they were surprised because of the lab had not found the second feather. >> bill peterson was interested in the results, too. a review of the slides showed what? traces of bird feather? >> yes. yes. exactly right. in her hair. another very, very compelling fact. >> reporter: what was most compelling about the idea that an owl attacked kathleen, the supporters thought, was how it accounted for the distinctive lacerations on her scalp. had the three main talons of an owl, like these, caused this bleeding head wound when it swooped down? symmetrical tears.