The special circumstance accompanies six additional criminal counts tied to an alleged early-morning attack on tenant Eric Bigone.
SAN FRANCISCO, CA — A special-circumstance allegation that a former dentist lay in wait before killing his tenant has placed the possibility of life without parole at the center of a San Francisco murder prosecution involving arson and an allegedly silenced automatic firearm.
Philippe Chagniot, 68, pleaded not guilty May 29 to the murder of Eric Bigone, 58, and to six additional felony counts. Prosecutors allege Chagniot went to Bigone’s Outer Sunset home before dawn May 17, interfered with nearby cameras, set a fire on a car and hid until Bigone came outside. The complaint accuses Chagniot of approaching from behind and opening fire with a fully automatic MAC-10 fitted with a silencer. Chagniot remains in custody, and the allegations have not been proved.
California’s lying-in-wait special circumstance is not merely another description of the killing alleged in the complaint. It is a separate accusation that can sharply increase the punishment attached to a murder conviction. Prosecutors must establish the elements required by law, including a period of concealment and watching or waiting, followed by a surprise attack on an unsuspecting victim. The state’s theory appears to rely on the alleged disguise, the damaged cameras, the deliberately placed fire and the claim that Chagniot waited out of view before approaching Bigone.
The complaint charges murder and alleges that Chagniot personally used and intentionally discharged a firearm, causing Bigone’s death. That firearm allegation could add punishment if a jury finds it true. Prosecutors also filed one count each of assault with an automatic firearm and arson. Three more counts accuse Chagniot of unlawfully possessing an automatic firearm, a silencer and a high-capacity magazine. Each charge addresses a different alleged act or item, and each carries elements that prosecutors must prove independently.
The weapons counts are important because the prosecution is not treating the gun merely as the instrument involved in the homicide. Authorities allege the firearm itself was capable of fully automatic fire and that it was accompanied by two restricted accessories: a device designed to suppress sound and a magazine capable of holding more ammunition than California law generally permits. The complaint’s assault count further alleges that Chagniot used an automatic firearm against Bigone. Prosecutors have not publicly released laboratory reports establishing that a weapon recovered during the investigation fired the shots that killed him.
Arson also functions as more than a background allegation in the prosecution’s account. Court documents say Chagniot placed burning material on top of a car parked outside Bigone’s residence. Prosecutors contend the fire was intended to prompt Bigone to leave the house, making it both an alleged felony and a step in the larger plan. Bigone reportedly came outside with a shovel and tried to remove the burning material. That response, authorities say, placed him where the hidden attacker expected him to be.
The District Attorney’s Office said surveillance video captured a masked person in dark clothing arriving by bicycle at about 5:09 a.m. Prosecutors identify that person as Chagniot. The person allegedly spray-painted surveillance-camera lenses before starting the fire and moving to a concealed position. When Bigone emerged, prosecutors say Chagniot approached from behind and shot him in the back. They further allege that after Bigone fell, Chagniot stood over him and fired more shots before leaving the neighborhood by bicycle.
Police officers arrived in the 2500 block of 46th Avenue after receiving a report of gunfire. They found Bigone suffering from multiple wounds and attempted to render aid. Paramedics also responded, but Bigone died at the scene. The restrained language of the criminal complaint does not lessen the seriousness of the allegations: Prosecutors are describing a deliberate attack carried out after efforts to limit observation and create a reason for the victim to step outside.
Investigators said the very camera network that was allegedly targeted helped them identify a suspect. Officers gathered video from other locations and used Flock license-plate-reading cameras to follow the path of the cyclist. According to prosecutors, the records showed travel by bicycle and then by vehicle, allowing police to trace movements between Chagniot’s home and Bigone’s residence before and after the shooting. That claimed reconstruction is likely to become a major issue as the case advances.
Surveillance evidence can show time, location, clothing, vehicles and routes, but it does not automatically establish identity. Prosecutors may seek to combine the recordings with vehicle records, items recovered in searches, digital evidence, witness testimony and forensic analysis. The defense may examine whether the images clearly show the person involved, whether timestamps were reliable, how investigators linked separate recordings and whether other explanations fit the travel pattern. Those questions are ordinarily tested through motions, cross-examination and expert testimony rather than settled by the filing of charges.
Police arrested Chagniot on May 27 and searched his residence. Authorities said they seized evidence tied to the case, while reporting from the arraignment identified a machine gun, silencer and high-capacity magazine among the items allegedly found. The public record has not yet established the results of ballistic, fingerprint or DNA examinations. A recovered object can support a charge, but the prosecution must still prove who possessed it, whether possession was unlawful and, when relevant, whether it was connected to the charged shooting.
At the arraignment, defense attorney Michael Cardoza entered not guilty pleas to every count and rejected the prosecution’s allegations. A plea is the accused person’s formal response to the charges, not an evidentiary hearing. The judge did not decide whether Chagniot committed the crimes. His continued detention likewise is not a finding of guilt. Prosecutors asked that he be held without bail because of the danger they believe he poses, and the defense did not seek immediate release at that appearance.
The charging decision places the burden entirely on the District Attorney’s Office. Prosecutors must first show sufficient evidence to keep the case moving, generally through a preliminary hearing. If the judge finds probable cause, the case may proceed toward trial, where every element of every count must be established beyond a reasonable doubt. The defense does not have to prove innocence. It can prevail by showing that the prosecution has not met its burden or by persuading jurors that reasonable doubt remains about identity, intent, evidence or another required element.
Authorities have confirmed that Chagniot was Bigone’s landlord, but they have not publicly announced a motive as part of the criminal prosecution. The landlord-tenant relationship supplies context, yet it does not prove planning, intent or identity. Prosecutors have so far emphasized the alleged conduct visible on recordings and the equipment they say was recovered. Motive is not always a required element of murder, though evidence explaining why an attack occurred can affect how jurors assess intent and the overall prosecution theory.
The case is expected to return to San Francisco Superior Court in late August for proceedings related to the preliminary hearing. No trial date has been set, and the police investigation remains active. Chagniot continues to be held in custody and is presumed innocent while prosecutors prepare to defend the murder charge, the special circumstance and each related felony in court.
Author note: Last updated July 18, 2026.