EDGARTOWN — The mother of a Vineyard Haven man who died of a drug overdose in April said she would continue to seek justice for her son despite a decision by the Cape and Islands District Attorney’s Office on Thursday not to pursue a manslaughter charge in the case.

Brenda Williston-Floyd, of Fairhaven, filed a criminal complaint in November seeking to charge Aaron Bezahler, 22, of Edgartown, with manslaughter. Bezahler, she says, sold her son, Antone Silvia, the fentanyl-laced heroin that killed him.

A clerk magistrate ruled that the charge could go forward. But in a notice filed in Edgartown District Court on Thursday, the district attorney’s office said it would not pursue it because the evidence in the case was insufficient to prove manslaughter. Bezahler does face two drug-related charges.

Williston-Floyd said she was upset by the decision not to prosecute manslaughter and planned to consult a lawyer about her next options.

“I’m not going to stop,” she said. “I don’t feel it’s right that he can walk the street and do that to someone else’s child.”

State police troopers found Silvia, 26, dead in the bathroom of his studio apartment April 23 with an uncapped syringe in his right hand, according to a police report. Silvia died of acute fentanyl and ethanol intoxication, according to an autopsy report.

Through text messages on Silvia’s phone, detectives determined that Silvia met Bezahler to buy heroin on the night of April 20, according to a police report. That was the last day people close to Silvia reported hearing from him and the last day he used his phone.

An analysis of Bezahler’s phone records revealed other texts that were consistent with drug distribution, the report states.

Bezahler was charged with distribution of a class A drug and conspiracy to violate drug law, according to court documents. He is scheduled to go on trial in March.

Bezahler’s attorney, Jennifer Marcus, filed a motion asking that evidence related to Silvia’s death not be admitted at trial because it was irrelevant to the charges and would only serve to inflame a jury.

Judge Thomas Kirkman ruled that some evidence pertaining to Silvia’s death, including a description of the scene where his body was found, was relevant to the case and could be admitted. But he issued instructions for how the evidence could be handled at trial to limit its prejudicial effect, according to a court order.

In her criminal complaint, Williston-Floyd wrote that Bezahler’s negligence caused her son’s death.

“He was not honest with Antone and sold him heroin laced with fentanyl,” she wrote. “So, by Antone thinking he was taking heroin, he gave himself a dosage that he knew he could handle. Since what he was given was fentanyl, it ended up being a lethal dose.”

Silvia was a good-hearted person who helped coach youth sports and was always ready to lend a helping hand, his mother said. She said she did not think he was a regular drug user because she would have known about it. The two were extremely close and talked every evening.

“Every day at five o’clock I still look at my phone,” she said.

Silvia’s family has been struggling with his loss, she said. He left behind an older brother and a 9-year-old son.

“We lost a wonderful person,” she said.

In her mind, the only just punishment for Bezahler is life in prison. By seeking justice for her son, she said, she hoped she could have an impact on others who have been through the same thing.

“I’m just trying to get justice for a lot of kids out there,” she said. “The law system needs to change.”

The state Supreme Judicial Court ruled in 1990 that heroin dealers could be charged with manslaughter, noting that 225 to 315 people in the state died from the drug between March 1987 and 1988. The overdose rate has skyrocketed since then, in large part because fentanyl has been added to the mixture.

Falmouth District Judge Christopher Welch has offered written justification of higher-than-normal bail is some recent opioid distribution cases, saying fentanyl likely would result in a death and “a potential legally viable charge of manslaughter.”

The Cape and Islands District Attorney’s Office has prosecuted several manslaughter cases against defendants whose drug dealing directly resulted in a death, O’Keefe previously told the Times.

But prosecuting a manslaughter case against a drug dealer is not easy, because the district attorney must prove which drugs caused the victim’s fatal overdose and that the defendant is the one who provided them, O’Keefe said at the time.