On August 6, 1974, Kathleen Smith, a 17-year-old Oakland prostitute was shot; she died three months later. According to the prosecutor handling the case and other sources, Newton shot Smith after a casual exchange on the street during which she referred to him as "Baby", a childhood nickname he hated. He was arrested on murder charges, then released for lack of evidence.
Similarly, Newton assaulted his tailor, Preston Callins, after Callins called him "Baby". Newton posted bond after being arrested for pistol-whipping Callins. Then Newton was arrested a second time for the murder of Smith, but he was able to post an additional $80,000 bond, thus securing his release until trial.
Rather than go to trial, Newton and girlfriend Gwen Fountaine fled to Havana, Cuba to avoid prosecution on the two charges, living there until 1977. Elaine Brown took over as chairperson of the Black Panther Party in his absence. Newton returned to the United States in 1977 to stand trial for the murder of Smith and the assault on Callins.
In October 1977 three Black Panthers attempted to assassinate Crystal Gray, one of the prostitutes present the day of Kathleen Smith’s murder and a key prosecution witness in Newton's upcoming trial. Unbeknownst to the assailants, they attacked the wrong house and the occupant returned fire. During the shootout one of the Panthers, Louis Johnson, was killed and the other two assailants escaped. One of the two surviving assassins, Flores Forbes, fled to Las Vegas, Nevada with the help of Panther paramedic Nelson Malloy. Fearing that Malloy would discover the truth behind the botched assassination attempt, Newton allegedly ordered a “house cleaning”, and Malloy was shot and buried alive in the desert. Although permanently paralyzed from the waist down, Malloy recovered from the assault and told police that fellow Panthers Rollin Reid and Allen Lewis were behind his attempted murder. Newton denied any involvement or knowledge and said the events “might have been the result of overzealous party members”.
During Newton's trial for assaulting Preston Callins, Callins changed his testimony several times and eventually told the jury that he did not know who assaulted him. Newton was acquitted of the assault in September 1978, but was convicted on two counts of illegal firearms possession.
After two trials and two deadlocked juries, the prosecution decided not to retry Newton for Smith’s murder.
During later years, in discussion with friend and sociobiologist Robert Trivers, Newton referred to the killing of Kathleen Smith as "my first non-political murder," and admitted he felt some guilt about killing her.