William Costa, 68, was killed in Manteca, California, on July 20, 2020. Investigators determined his death was not from natural causes and treated it as a violent crime. Local authorities later developed multiple leads, identified several persons of interest, and conducted numerous interviews.

Evidence developed during the inquiry suggested the killing may have been part of a broader criminal conspiracy, prompting federal agencies to join the investigation. Several people were arrested; charges reported included murder, conspiracy to commit murder, and related offenses. The subsequent proceedings involved multiple defendants, extensive evidence, testimony from forensic and behavioral experts, and defense challenges to the investigation and evidence.

The case drew sustained attention in Manteca and highlighted cooperation between local and federal law enforcement. If anyone knew William Costa, his movements before July 20, 2020, or has information about the conspiracy alleged in this case, please come forward.