MARTINEZ — Just three hours after they started deliberating, a Contra Costa County jury Friday convicted an Oakland man of murdering his ex-girlfriend after an argument outside an Antioch convenience store.
Oakland resident Thomas Williams Jr., 37, had argued that he committed manslaughter, not murder, when he shot and killed Cynthia Flores-Crose inside a Quik Stop in May 2016.

The trial lasted a little more than a week, and a large group of Flores-Crose’s friends and family packed the courthouse each day. Her aunt, Sandy Sullivan, said the family was satisfied with the verdict but was still mourning Flores-Crose, who she described as “beautiful, smart, sweet and gentle.”
“She was too kind for this world. Never saw the bad in people,” Sullivan said. “That was our beautiful Cynthia. The world is a darker place without her.”
Convicted of first-degree murder, attempted murder and gun enhancements, Williams is now facing at least 40 years to life in prison.
The motive, prosecutors said, stemmed from Williams’ inability to handle rejection. Right before the shooting, Flores-Crose and Williams had an intense discussion where he asked to re-start their relationship, but she refused.
So Williams followed her into the store, punched her, knocking he down, then went to his car and retrieved a gun. He backed away the store clerk, then stood over Flores-Crose and shot her as she screamed in fear. Then he turned the gun on the clerk, Thomas Payne, and shot him in the arm. Payne survived.
A security camera, equipped with a microphone, captured the whole thing.
Williams testified the morning of the shooting, he called in sick from work and headed out to Antioch to surprise his children he had from another relationship. They lived near the Quik Stop, where Flores-Crose stopped by each day on her way to work. She had just gotten a new job as a care giver — which she called a promotion — and was “excited for the future because her future looked bright and positive,” Sullivan said.
“Not a mean or aggressive bone in her body,” Sullivan said. “She loved children and the elderly.”
Williams said on the stand that running into Flores-Crose that day was a coincidence. Prosecutors don’t believe him, they think he was waiting there, and used a dispute over a car title as a “linchpin” to force a conversation and bring up their defunct relationship.
“There were choices all morning long by the defendant that culminated in the defendant’s choice to kill,” prosecutor Alison Chandler told jurors on Thursday, during closing arguments. “He premeditated that murder.”
Williams’ defense attorney, Kirk Athanasiou, argued that Williams’ emotions had “clouded his reasoning” when he became scared Flores-Crose would “make a scene.” Williams testified he was afraid of losing his kids if the police were called, and that he had no memory starting from about the point he walked into the store to punch Flores-Crose until a few minutes after he killed her.
“He had no idea what he was doing,” Athanasiou told jurors Thursday. “He couldn’t have formulated intent to assault anyone.”
But Chandler said Williams’ actions showed he was in a “homicidal rage,” not a state of mind that would warrant a lesser charge, like manslaughter.
“This is not rocket science,” she told the jury on rebuttal.