Penalty Phase Began in 2012 Triple Murder Trial
A jury is deciding if Alberto Sierra will face the death penalty for the 2012 killings.
Updated on Oct. 13, 2026 in Violence
Jurors in the trial of Alberto Sierra, who pleaded guilty to the 2012 murders of Gladys Machado and young sisters Julia and Daniela Padrino, heard testimony during the ongoing penalty phase. The proceedings will determine whether the 42-year-old defendant receives the death penalty.
Why it matters
The outcome of this penalty phase rests on whether the jury finds the defendant's childhood brain injury sufficient to influence his sentencing. The case marks a final legal chapter for the families of the victims, who were suffocated 14 years ago.
The jury is weighing the life of 42-year-old Alberto Sierra, who pleaded guilty to killing 29-year-old Gladys Machado and two sisters, aged 6 and 3, in 2012. The final sentencing decision remains unresolved.
The players
Alberto Sierra
The 42-year-old defendant who pleaded guilty to the 2012 murders of three victims.
Mercedes Pedraza
A witness who provided testimony during the penalty phase of the trial.
Dr. Erin Bigler
A psychologist who testified about the defendant's frontal lobe injury via Zoom.
The details
The defense is arguing that a traumatic brain injury sustained by Sierra in a traffic accident at age 12 significantly altered his decision-making capacity. Dr. Erin Bigler provided expert testimony via Zoom, presenting brain scans to the jury to support this claim. Mercedes Pedraza also took the stand during the current phase, which began in October.
Timeline
The crimes occurred in 2012.
Alberto Sierra pleaded guilty in August 2026.
Mercedes Pedraza testified on October 13, 2026.
The trial is scheduled to resume on Wednesday, October 14, 2026.
Beyond the 305
The defense's focus on the defendant's childhood traumatic brain injury follows the pattern of using neurocognitive evidence to challenge capital sentencing eligibility as established in cases like Atkins v. Virginia. This trial represents another local effort to weigh medical history against state-mandated penalties for violent crime.
This case marks a conclusion to a long-standing homicide investigation for the local community. Residents should monitor the jury's upcoming decision for the final resolution of this case.
The takeaway
The jury must weigh medical testimony regarding brain injury against the defendant's guilty plea for the 2012 crimes. Watch for the final sentencing verdict as the trial continues through the week.
What happens next
The trial is set to resume Wednesday morning, October 14, 2026.
Further reading
For more updates on local criminal proceedings, visit Violence.
