Prosecutors allege Philippe Chagniot used fire, damaged cameras and a silenced automatic weapon to carry out a planned attack.

SAN FRANCISCO, CA — A retired dentist accused of setting a car on fire to draw his tenant outside before shooting him with a silenced automatic firearm has pleaded not guilty to murder, arson and a series of weapons charges in San Francisco Superior Court.

Philippe Chagniot, 68, is charged in the May 17 killing of 58-year-old Eric Bigone in the Outer Sunset neighborhood. The murder count carries an allegation that Chagniot personally used a firearm and a special-circumstance allegation that he killed Bigone while lying in wait. Prosecutors also charged him with assault with an automatic firearm, arson, possession of an automatic firearm, possession of a silencer and possession of a high-capacity magazine. Chagniot entered not guilty pleas to all charges May 29 and remains in custody while the criminal case moves forward.

The special-circumstance allegation is among the most serious parts of the prosecution’s case. It requires prosecutors to prove more than an intentional killing. They allege Chagniot concealed his purpose, waited for an opportunity to attack and surprised Bigone from a position of advantage. A conviction for murder with the lying-in-wait special circumstance could expose Chagniot to life in prison without the possibility of parole. The allegation, like every charge in the case, must be proved in court beyond a reasonable doubt. Chagniot is presumed innocent unless he is convicted.

The criminal complaint identifies murder under California Penal Code Section 187 and adds a firearm allegation alleging that Chagniot personally and intentionally discharged a weapon, causing death. Prosecutors separately charged assault with an automatic firearm, an offense focused on the alleged use of a fully automatic weapon against another person. The arson count is based on the fire allegedly placed on top of a car outside Bigone’s home. Three possession counts address the alleged automatic firearm, silencer and high-capacity magazine. Those charges allow prosecutors to seek punishment for conduct surrounding the killing even apart from the murder allegation.

According to the District Attorney’s Office, surveillance recordings show a person prosecutors identify as Chagniot approaching Bigone’s residence by bicycle at about 5:09 a.m. The person was dressed in dark clothing and wore a mask, court documents allege. Prosecutors say the person spray-painted several surveillance cameras in an effort to block their view, then placed burning material on a vehicle parked outside the residence. He allegedly moved away from the immediate area and waited for someone to respond to the fire.

Bigone came out of the house carrying a shovel and began trying to remove the burning material, prosecutors said. While Bigone was focused on the fire, Chagniot allegedly approached him from behind with a fully automatic MAC-10 equipped with a silencer and shot him in the back. Prosecutors allege Chagniot then stood over Bigone and fired again after he had fallen. Police officers responding to the 2500 block of 46th Avenue found Bigone with multiple gunshot wounds. Officers and paramedics tried to help him, but he was pronounced dead at the scene.

The alleged sequence supports several distinct parts of the charging document. The fire is the basis of the arson count and, in the prosecution’s theory, served as a way to bring Bigone outside. The reported effort to obscure cameras and the period of waiting are central to the lying-in-wait allegation. The type of weapon described by prosecutors is the basis for the assault and possession charges, while the alleged use of that weapon is attached to the murder count as an enhancement. Prosecutors will still have to connect Chagniot to each act with admissible evidence rather than relying only on the sequence described in the complaint.

Investigators said they used surveillance recordings and automated license-plate-reading cameras to reconstruct the suspect’s movements. Police allegedly followed the route of a cyclist leaving the area, connected the bicycle trip to a vehicle and traced that vehicle toward Chagniot’s home. Authorities said the recordings showed movement between Chagniot’s residence and Bigone’s home before and after the shooting. Police arrested Chagniot on May 27, 10 days after the killing, and served a search warrant at his residence.

Investigators reported recovering evidence they believe is connected to the case. Local reporting on the court proceedings said police found a machine gun, a silencer and a high-capacity magazine at Chagniot’s residence. Whether forensic testing links any recovered firearm, ammunition or accessory to the shooting has not been publicly established. Prosecutors will be required to authenticate physical evidence and demonstrate how it relates to the charged offenses. The defense may challenge the searches, the identification of the person in the recordings, the handling of evidence or any claimed connection between seized items and Bigone’s death.

Chagniot appeared in custody at his arraignment, where defense attorney Michael Cardoza entered not guilty pleas on his behalf and denied the allegations. The defense did not seek his immediate release, although it may raise the issue of bail later. Prosecutors filed a motion asking the court to hold Chagniot without bail, arguing that he presents a public-safety risk. The detention question is separate from guilt: A judge considering custody before trial evaluates factors such as the seriousness of the charges, the strength of the preliminary evidence and the risk of danger or failure to appear.

The next major stage is expected to be a preliminary hearing, unless the parties first resolve motions or scheduling issues. At that hearing, prosecutors must present enough evidence for a judge to find probable cause that crimes occurred and that Chagniot committed them. The standard is lower than the proof beyond a reasonable doubt required at trial. Witnesses may testify, investigators may describe evidence they collected, and the defense may cross-examine them. A finding of probable cause would allow the charges to continue toward trial but would not be a determination that Chagniot is guilty.

Authorities have not announced a confirmed motive in the criminal case. Police Chief Derrick Lew said Chagniot was Bigone’s landlord, and court reporting indicated Bigone had rented the home since 2023. That relationship may provide context, but it does not by itself establish why the shooting occurred. Prosecutors have publicly concentrated on the alleged planning, the surveillance trail, the fire and the weapons they say were used. Any motive theory presented at trial would need support from testimony, records, communications or other evidence admitted by the court.

Chagniot had been licensed as a California dentist for decades, though state records cited by news organizations showed the license expired in 2024. His former profession is not part of the criminal charges and does not determine the case. The prosecution centers on what allegedly happened before dawn May 17, the identity of the person recorded near the residence and the physical evidence collected during the investigation. Friends remembered Bigone as a grandfather, public utility worker, musician and boxing supporter with longstanding ties to the city’s west side.

Chagniot remains jailed as the court prepares for further proceedings. He is expected to return to court in late August for scheduling connected to the preliminary hearing. The homicide investigation also remains open, and no trial date has been announced. Until a judge or jury resolves the charges, the allegations in the complaint remain unproved.

Author note: Last updated July 18, 2026.