Arthur "Boo" Radley grew up in a strict household and was under the constant supervision of his cruel father after he had a minor run-in with the law as an adolescent. According to Miss Maudie, Arthur "Boo" Radley was always a nice child, who was polite and respectful whenever she spoke to him. After getting into trouble with the Cunningham boys, Boo's authoritative father prohibited from leaving the house and Boo Radley remained indoors for the majority of his life. It is implied that Boo Radley was a typical child, who was not mentally disabled as an adolescent. While nobody can say for certain what means of intimidation or violence Mr. Radley utilized to keep his son from leaving the house, it certainly damaged Boo emotionally and mentally.

As the story progresses, Scout and Jem discover that Boo is a compassionate, generous man, who gives them gifts and offers them protection when they need it the most. Following Bob Ewell's attack, Scout finally meets Boo Radley face-to-face and he is depicted as a childlike, shy adult, who speaks softly and requests that Scout walk him home. Boo Radley's demeanor at the end of the novel indicates that he has been emotionally and mentally scarred after suffering unknown forms of abuse at the hands of his cruel father and brother. Judging from Miss Maudie's comments and Boo's benevolent nature, one can surmise that he experienced a significant amount of trauma while he was locked in his own house. The mysteries surrounding Boo's life behind the doors of his home highlight his enigmatic nature and contribute to his characterization as a symbolic mockingbird.

Boo Radley is a powerful symbol of goodness although he is originally blanketed in a shroud of creepiness, leaving little presents for Scout and Jem and emerging at just the right moments to save them from harm. He was originally an intelligent child emotionally, but he was emotionally damaged by his cruel father, and essentially put under "house arrest" for most of his life. To specifically answer your question, yes Boo is one of the novel's “mockingbirds,” a good person injured by the evil of mankind. He provides a perfect example of the threat that evil poses to innocence and goodness. Check the link below for more information. Hope this helps you.