A Richmond man who was once sentenced to life in prison for a Halloween-night killing has instead agreed to serve 17 years and eight months, after an appellate court found the trial judge failed to properly instruct jurors on self-defense. Thadeus Colley, now 50, pleaded no contest to voluntary manslaughter in the 2018 shooting death of 42-year-old Jamaa Anderson, closing out a case that had already sent him to prison once under a since-overturned murder conviction.
According to The Mercury News, Anderson was shot around 1:40 a.m. on November 2, 2018, on the 3100 block of Deseret Drive in Richmond, following a fight with Colley over an iPad. He was taken to a hospital but died later that same day. Richmond police arrested Colley about a week later, on November 9, 2018, publicly crediting community support and detective work for cracking the difficult Halloween-weekend case, per SFGATE.
Colley was convicted of murder in 2019 and sentenced to life in prison in 2021, court records show. But that same year, an appellate court ruled that the trial judge should have instructed the jury on the possibility that Colley acted in self-defense — a decision that ultimately unraveled the conviction.
How a Jury Instruction Flipped the Case
The legal issue centers on what California law calls imperfect self-defense, a doctrine under Penal Code Section 192 that reduces a murder charge to voluntary manslaughter when a defendant kills based on an honest but objectively unreasonable belief that deadly force was necessary to prevent imminent death or great bodily harm, according to the Shouse Law Group. California appellate courts treat a trial judge's failure to give that instruction, when supported by substantial evidence, as prejudicial error reviewed under the People v. Watson standard, the San Francisco Criminal Lawyer Blog explains.
That ruling left the murder conviction overturned. The case ultimately ended in a plea deal in January 2026, according to court records cited by the Mercury News report. The deal had not been previously reported before the paper's Sunday story.
Building a 17-Year, Eight-Month Sentence
Voluntary manslaughter alone carries a state prison base sentence of three, six, or eleven years under Penal Code Section 193(a), per Eisner Gorin LLP. Colley's negotiated term of 17 years and eight months exceeds even the maximum base sentence, but the available sources do not identify why it is longer. The article's cited Bulldog Law analysis does not establish whether any firearm enhancement was imposed or what terms might apply.
California trial judges also hold statutory authority, under Senate Bill 620 and Penal Code Section 1385, to strike or dismiss those firearm enhancements in the interest of justice during plea negotiations, the same Bulldog Law analysis notes — a tool prosecutors and defense attorneys routinely use to arrive at agreed-upon sentences rather than risk a full retrial. The case involved the Contra Costa County District Attorney's Office and a final plea agreement.
Open Questions and Victim Notification
It remains unclear whether Anderson's family was formally notified of or agreed with the plea terms. In a different case, Richmondside reported an alleged failure to notify a family. How much custody credit Colley has accumulated since his November 2018 arrest, and his projected release date, were not addressed in available court records.
Colley is currently housed at the California Substance Abuse Treatment Facility and State Prison in Corcoran, according to CDCR background information.
A Case From a Different Era of Richmond Violence
Anderson's killing took place during a period of markedly higher violence in Richmond than the city sees today. Richmond recorded just six homicides in 2025, the lowest annual total in the city's modern recorded history and a steep drop from an all-time peak of 61 killings in 1991, Hoodline previously reported. That long-term decline has coincided with community intervention efforts, though the 2018 shooting predates much of that shift.
