Complex sentence: Neighbors and relatives would recall Berkowitz as difficult, spoiled, and a bully--his adoptive parents consulted at least one psychotherapist due to his misconduct--but his misbehavior never resulted in legal intervention or serious mention in his school records.
Split into simpler sentences: Neighbors and relatives would recall Berkowitz as difficult, spoiled, and a bully. His adoptive parents consulted at least one psychotherapist due to his misconduct, but his misbehavior never resulted in legal intervention or serious mention in his school records.