Changeling by angeline jolie

I love this movie and here it's the story.

Wineville Chicken Coop Murders

(after that incident, the city now is called Mira Loma.)
It was a series of kidnappings and murders of young boys occurring in Los Angeles and Riverside County, California in 1928.
In 1926, ranch owner Gordon Stewart Northcott and his 14-year-old nephew, Sanford Clark.
Northcott had beaten and sexually abused Clark.
Clark claimed that Northcott had kidnapped, molested, and killed several young boys.
Clark said quicklime was used to dispose of the remains, and the bones had been dumped in the desert.

Christine and Walter Collins

Nine year old Walter Collins went missing from Los Angeles on March 10, 1928.The police faced negative publicity and increasing public pressure to solve the case, until five months after Walter's disappearance, when a boy claiming to be Walter was found in DeKalb, Illinois.A public reunion was organized by the police, who hoped to negate the bad publicity they had received for their inability to solve this case and others. They also hoped the uplifting human interest story would deflect attention from a series of corruption scandals that had sullied the department's reputation. At the reunion, Christine Collins claimed that the boy was not Walter. She was told by the officer in charge of the case, police Captain J.J Jones, to take the boy home to "try him out for a couple of weeks," and Collins agreed.Three weeks later, Christine Collins returned to see Captain Jones and persisted in her claim that the boy was not Walter. Even though she was armed with dental records proving her case, Jones had Collins committed to the psychiatric ward at Los Angeles County Hospital under a "Code 12" internment—a term used to jail or commit someone who was deemed difficult or an inconvenience.

During Collins' incarceration, Jones questioned the boy, who admitted to being 12-year-old Arthur Hutchins Jr., a runaway from Illinois, but who was originally from Iowa.His motive was to get to Hollywood so he could meet his favorite actor, Tom Mix. Collins was released ten days after Hutchins admitted that he was not her son, and filed a lawsuit against the Los Angeles Police Department.Five years after Northcott's execution, one of the boys that Northcott allegedly killed was found alive and well. As Walter Collins' body had not been found, Christine Collins still hoped that Walter had survived. She continued to search for him for the rest of her life, but she died without ever knowing her son's fate.