LONG BEACH, Calif.—A man convicted of voluntary manslaughter for chasing after and fatally stabbing a man who had confronted him in the Belmont Shore area of Long Beach was sentenced Jan. 17 to 14 years and six months in prison.

A Long Beach jury last June deliberated about a day before finding true an allegation that Sergio Alvarez, now 28, used a knife to stab 33-year-old Gavin Clason.

Jurors also convicted Mr. Alvarez of dissuading a witness from reporting a crime, but acquitted him of the more serious count of second-degree murder for the March 6, 2022, killing—an act that Mr. Alvarez’s attorney contended was committed in self-defense.

Superior Court Judge Richard M. Goul handed down the sentence on Wednesday.

“This has been a difficult week,” the victim’s father, Norman, said outside court following the verdict in June. “I don’t think he deserved to die the way he did here ... We’re just really going to miss him.”

Deputy District Attorney Jacqueline Mac told jurors in her closing argument that Mr. Clason initially ran toward Mr. Alvarez, but said “there was no danger to him (the defendant) at the time he chased Gavin down and stabbed him in the street.”

Ms. Mac said Mr. Alvarez “did not have a reasonable belief in this case that his life was in danger,” telling jurors he “went overboard” and stabbed Mr. Clason twice while he was on the ground.

Mr. Alvarez told a co-worker at a nearby fast-food restaurant not to tell police what happened and went home and shaved his hair in an effort to cover his tracks, Ms. Mac said.

Defense attorney Joe Gibbons countered that his client—5 feet, 1 inch tall and 122 pounds—was with a friend and was riding a skateboard when he was confronted by Mr. Clason, whom he said was 5 feet, 11 inches tall and 190 pounds, acting erratically and later determined to have a blood-alcohol content of more than three times considered the legal limit for impairment while driving.

Mr. Gibbons noted that he had told jurors at the start of the trial that “this was going to be a self-defense case,” saying that Mr. Clason “went after the littlest guy” who “had a right to be scared” and “had a right to defend himself.”

Mr. Gibbons noted that his client—who testified in his own defense—admitted that he had stabbed Mr. Clason.

“I submit to you he acted in a very, very reasonable way given the circumstances,” Mr. Gibbons said, in urging jurors to acquit his client of murder or to consider the lesser crimes of voluntary manslaughter or involuntary manslaughter.

Mr. Gibbons also told the panel that he thought the prosecution had not made its case on a robbery charge involving items belonging to Mr. Clason that were picked up later from the sidewalk, and said he would leave it up to the jury to decide whether Mr. Alvarez had tried to persuade a witness not to call police.

In her rebuttal argument, Ms. Mac countered that Mr. Alvarez was “acting out of anger,” not in self-defense. She noted that jurors had multiple surveillance video clips to review of the initial confrontation and the subsequent stabbing.

Mr. Clason was pronounced dead on the sidewalk in the 3900 block of East Ocean Boulevard.

Mr. Alvarez was arrested the following day, and has remained behind bars since then, according to jail records.