Nassau DA: Melbis Hernandez, convicted of murder and assault, sentenced to up to life in prison

A homeless man who stabbed two people in Hempstead — one fatally — within a month of each other in the fall of 2023 was sentenced Monday to up to life in prison.

After two trials, Melbis Hernandez, 39, was convicted of second-degree murder, second-degree attempted murder and attempted assault in the first degree for the attacks on the two men.

Building security footage showed Hernandez lying in wait for the first victim, his ex-girlfriend’s stepfather, who had kicked him out of the apartment at 45 Jackson St., according to court records.

When the 49-year-old man got home from work around 9:30 p.m. on Sept. 28, 2023, Hernandez confronted him, stabbing him once in the left side of the chest, prosecutors said.

The man fled through a parking lot with Hernandez pursuing him, authorities said. When the victim approached a police car, Hernandez stopped chasing him.

Less than a month later, Hernandez hung out in the stairwell of the same Jackson Street building waiting for Marlon Rivas Aguilar, 53, to enter, according to court testimony.

As he did, Hernandez stabbed him three times in the back, then fled, leaving his victim to die in the stairwell, prosecutors said.

Rivas Aguilar was found three hours later, dead in the doorway of the building.

Police found the knife in a nearby sewer with Hernandez’s DNA on it, according to court records. Prosecutors said that investigators also found DNA on a Sprite can discovered in the window of the stairwell where Hernandez waited for Rivas Aguilar.

Nassau County District Attorney Anne Donnelly called it “a random, brutal act of violence.”

“My prosecutors worked tirelessly to bring justice to the victims and their families, and today’s sentence ensures a dangerous criminal is off our streets potentially for the rest of his life,” Donnelly said.

Both crimes were caught on surveillance video. prosecutors said.

The victim in the first stabbing recognized Hernandez in the security footage and police arrested him on Nov. 5.

At Hernandez's first trial on July 23, 2025, two jurors complained that a third had not followed the judge’s instructions and had looked up the term “reasonable doubt.”

Juror 10 told state Supreme Court Justice Tammy Robbins that Juror 1 “had done research of legal terms and tried to share them with the Jury on how we should proceed," according to a motion for mistrial. Juror 10 also said that the wayward juror “does not understand the law as it was explained to us and is using speculation.”

In a second infraction, the jury foreman complained that Juror 1 had visited the scene of the crime and knew the age of the defendant, though it hadn’t been stated at trial.

Robbins granted a mistrial based on a motion by Hernandez’s first attorney, Steven Barnwell.

He was tried again and convicted on June 23, nearly a year after his mistrial.

After the verdict, one of the jurors recognized a member of the victim’s family in the courtroom, but a second request for a mistrial was denied.

His current defense lawyer, Gregory Madey, said he would appeal the verdict, adding that he believes the prosecution is flawed.

“It’s extremely prejudicial to try both crimes together. I think it’s hard for a jury to separate a stabbing that occurred one month from a murder that occurred one month later,” Madey said.