As is customary in criminal court cases, the prosecuting attorney calls a law enforcement officer and various experts to serve as witnesses for the prosecution. At the beginning of the trial of Tom Robinson, Mr. Gilmer calls on Sheriff Tate to testify on the details of the incident which is purportedly the cause of Robinson's arrest on a charge of rape.
Sheriff Tate is the first witness to be called. He testifies that Mr. Ewell came to "fetch" him on November twenty-first. Ewell told the sheriff "to get out to his house quick; some n****r'd raped his girl." When the sheriff arrived, Mayella Ewell was on the floor in the middle of the front room. Tate remarks that she looked "pretty well beat up," so he lifted Mayella to her feet and she washed her face in a bucket of water that was in the corner of the room. She then told the sheriff she was "all right." The Sheriff testifies, "I asked her who hurt her and she said it was Tom Robinson. He adds,
"—asked her if he beat her like that, she said yes he had. Asked her if he took advantage of her and she said yes he did. So I went down to Robinson's house and brought him back. She identified him as the one, so I took him in. That's all there was to it." (Ch. 17)
Mr. Gilmer addresses no more questions to Sheriff Tate. But on cross-examination, Atticus Finch asks pointedly, "Did you call a doctor, Sheriff? Did anybody call a doctor?" Sheriff Tate replies, "No sir." When Atticus asks why no one called a physician, Tate replies that he did not because he could tell that something had happened since Mayella was "mighty banged up." But Atticus repeats his question until Judge Taylor interrupts, "He's answered the question three times, Atticus. He didn't call a doctor." As Atticus responds, "I just wanted to make sure, Judge," a smile crosses the judge's face because he understands why Atticus has asked this question: There is no medical proof of rape, and there can be no professional testimony to this effect.
Another strong point for the defense of Tom Robinson is also made by Atticus as he continues to question Sheriff Tate. With the testimony that Atticus gets from the sheriff, it is established that Mayella was struck in her right eye and "banged up" on the right side. Atticus also establishes from Tate's testimony that Mayella's arms were bruised and there were finger marks on her throat.
"All around her throat? At the back of her neck?"
"I'd say they were all around, Mr. Finch." (Ch.17)
When Sheriff Tate concludes his testimony, Atticus knows that Tom Robinson could not have been the one who inflicted bruises and choking upon Mayella because he has only one good arm, and that one is his right arm. But, the marks on Mayella's face on the right side suggest that someone who is left-handed struck her. Also, it would be impossible for Tom to have choked Mayella as the sheriff describes her when she had marks all around her neck—marks that indicate an assaulter with two hands.