The plot of Lies He Told Me centers on the United States Federal Witness Protection Program (WITSEC). Marcie eventually discovers that her husband’s secretiveness and dishonesty stem from his status as a government-protected witness. WITSEC is designed to ensure the safety of witnesses and their immediate family members who testify against organized crime rings, drug cartels, terrorist organizations, and other dangerous criminal groups. The program is administered by the U.S. Marshals Service.

Witnesses are selected for the WITSEC scheme based on the seriousness of the case, the threats against them, and their willingness to cooperate. Participants are issued with new names and personal records, such as birth certificates and driver’s licenses. They are also relocated to undisclosed destinations, often far removed from their original homes. Witnesses are generally prohibited from contacting friends or family from their past lives. U.S. Marshals (such as Camille Striker in the novel) are responsible for supervising witnesses’ security.

Sammy “The Bull” Gravano was a notable real-life participant in the witness protection program. A high-ranking member of the Gambino crime family, he was involved in 19 murders but eventually turned informant on mob boss John Gotti in 1991. He cut a deal with the government, and his testimony led to Gotti’s life sentence in 1992. In exchange, Gravano was sentenced to just five years despite his serious crimes.

Patterson’s depiction of the conviction of mobster Michael Cagnina in Lies He Told Me is influenced by the circumstances in which the notorious Mafia boss Al Capone was arrested. As the FBI could not prove the extortion and murders he was undoubtedly responsible for, they prosecuted him for the lesser charge of tax evasion. A Chicago mobster, Capone was one of the most powerful criminals in American history, running a multi-million-dollar empire of bootlegging, gambling, racketeering, and murder during the Prohibition era (1920–1933). Despite his links to numerous crimes, Capone avoided conviction for murder and racketeering through bribery and the intimidation of witnesses. His failure to file tax returns for his earnings led to his conviction in 1931. Capone was sentenced to 11 years in federal prison, the harshest penalty for tax evasion at the time.