Massachusetts high court orders new trial in 2014 J'ouvert killing over flawed gunshot-residue evidence

Overview

Updated 2 hours ago

Keith Williams was convicted of first-degree murder for the 2014 shooting that killed Dawnn Jaffier during Boston's J'ouvert parade. On Tuesday, the state's highest court ordered a new trial, ruling the gunshot-residue evidence against him never met the standard for a positive test.

Prosecutors found two microscopic residue particles on Williams. A valid test requires three. The State Police lab technician who ran the test even called the result negative. The high court said prosecutors failed to explain why two particles still proved Williams fired the gun, and that the error was prejudicial enough to warrant a retrial.

Why it matters

The ruling restricts when Massachusetts courts can admit gunshot-residue evidence and may force prosecutors to retry cases built on sub-threshold tests.

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Key Indicators

Gunshot residue particles found on Williams

Below the 3-particle minimum for a positive test

Particles needed for a positive GSR test

Massachusetts State Police protocol at the time of trial

Convictions overturned or ordered for new trial by SJC

Williams in 2026, Colas in 2021

Years between the shooting and the new-trial ruling

August 2014 to September 2026

Voices

Curated perspectives — historical figures and your fellow readers.

Ever wondered what historical figures would say about today's headlines?

People Involved

Keith Williams

Convicted shooter, granted new trial

Awaiting Suffolk County DA decision on retrial

Dawnn Jaffier

Victim, 26-year-old youth worker

Deceased

Wesson Colas

Co-defendant, conviction overturned

Released after 2022 manslaughter plea

Elizabeth N. Dewar

Associate Justice, Massachusetts Supreme Judicial Court

Wrote the unanimous 2026 ruling

Robert F. Shaw Jr.

Williams's attorney

Representing Williams after the new-trial order

Kevin Hayden

Suffolk County District Attorney

Deciding whether to retry Williams

Organizations Involved

Massachusetts Supreme Judicial Court

State Supreme Court

Overturned or ordered new trials in both Jaffier convictions

The state's highest court, which reviews criminal convictions and interprets Massachusetts law.

Suffolk County District Attorney's Office

Prosecutorial Office

Reviewing whether to retry Williams

The prosecuting office for Boston and surrounding communities, deciding whether to retry Williams.

West End House

Youth Development Organization

Former employer of Dawnn Jaffier; keeps her legacy

A Boston youth development organization where Dawnn Jaffier worked as a mentor and program director.

Timeline

August 2014 September 2026

5 events Latest: Today

Tap a bar to jump to that date

September 2026
SJC orders new trial for Williams over GSR evidence
Today Legal

The Supreme Judicial Court rules unanimously that prosecutors presented gunshot-residue evidence below the three-particle threshold without explaining its reliability, a prejudicial error. The court rejects the defense request for outright acquittal.
Today
June 2022
Colas pleads guilty to manslaughter, released
Legal

Rather than face a retrial, Colas pleads guilty to involuntary manslaughter and is sentenced to seven years, which he has already served. (Date approximate; sources confirm the year.)
June 1st, 2022
February 2021
SJC overturns Colas's murder conviction
Legal

The Supreme Judicial Court rules there is no evidence Colas intended to kill Williams; pointing a gun is not enough to prove intent. The court orders a new trial or reduced charges for Colas.
February 22nd, 2021
June 2017
Williams and Colas convicted of first-degree murder
Legal

The two men are tried jointly and convicted of first-degree murder for Jaffier's killing. Both are sentenced to life in prison. (Date approximate; sources confirm the year.)
June 30th, 2017
August 2014
Dawnn Jaffier fatally shot during J'ouvert celebration
Incident

Youth worker Dawnn Jaffier, 26, is struck in the head by gunfire during an argument between Keith Williams and Wesson Colas in Dorchester. A second woman is wounded.
August 23rd, 2014 • early morning

Scenarios

Retrial convicts Williams of first-degree murder

Possible Resolves by End of 2027

Discussed by: Suffolk District Attorney's Office; the SJC's ruling notes surveillance footage shows Williams holding the murder weapon seconds after the shooting

District Attorney Kevin Hayden decides the other evidence is strong enough and retries Williams. Prosecutors lean on the surveillance video and eyewitness accounts rather than the discredited gunshot-residue testimony. The SJC has already said this evidence could support a premeditated murder conviction, so the retrial hinges on the jury's view of self-defense.

District attorney drops charges, Williams walks free

Unlikely Resolves by End of 2027

Discussed by: Robert F. Shaw Jr., Williams's attorney; the defense has argued the evidence was always thin and self-defense clear

Hayden's office concludes that without the gunshot-residue testimony, the case is too weak or too costly to retry. It files to dismiss the charges, and Williams is released after more than a decade in prison. The DA's office has said it is still reviewing the ruling, leaving this option open.

Williams pleads guilty to reduced charge, released

Possible Resolves by Q2 2028

Discussed by: Precedent set by Wesson Colas, who pleaded guilty to manslaughter in 2022 after his conviction was overturned

To avoid the risk of another life sentence, Williams accepts a plea to manslaughter or a lesser charge. He receives credit for time served and is released, mirroring exactly what Colas did after his conviction was overturned. The district attorney gets a conviction without the expense and uncertainty of a retrial.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

1980-2012

Santae Tribble Exoneration (2012)

Santae Tribble was convicted of murder in 1980 based largely on hair microscopy and served 28 years. DNA testing in 2012 proved the hair was not his, and he was exonerated.

Then

Tribble was freed and later received compensation.

Now

His case became a symbol of how forensic testimony can fail, contributing to reform efforts.

Why this matters now

It's a reminder that when a court lets scientifically weak evidence decide a murder case, the error may surface only years later, the same pattern the SJC identified in Williams's trial.

February 2009

NAS Forensic Science Report (2009)

The National Academy of Sciences published "Strengthening Forensic Science in the United States," a landmark review finding that most forensic disciplines, including gunshot-residue analysis, lacked validated standards. The report argued that many techniques offered in court had never been scientifically tested for reliability.

Then

The report pushed courts and crime labs to reconsider how forensic evidence is admitted and validated.

Now

It became the reference point for decades of challenges to forensic evidence, including bite marks, hair microscopy, and gunshot residue.

Why this matters now

The SJC's ruling that a sub-threshold gunshot-residue result lacked a foundation echoes the report's central critique: a forensic test is only as good as its validated standard.

2015

FBI Hair Microscopy Review (2015)

The FBI and the Innocence Project reviewed hundreds of cases involving hair microscopy and found that examiners gave flawed, scientifically unsupported testimony in 268 of the 268 trials examined. The FBI acknowledged the problem and began notifying defendants, some of whom were later exonerated.

Then

The review triggered re-examinations of convictions across the country and cast doubt on a technique used for decades.

Now

It became a cautionary example of confident-sounding forensic testimony that was later discredited.

Why this matters now

Like hair analysis, gunshot-residue evidence can look definitive in court while resting on a threshold a lab itself treats as advisory. The Jaffier case shows courts are increasingly willing to revisit such testimony.