He was trying to park his boss’s pickup truck in a private lot off Rhode Island Avenue and Second Street, near his home in Northeast Washington.

But Desmond Joseph, 41, was in a work zone and apparently had trouble reaching the space he needed. Witnesses told police that he got out of the truck and started tossing aside orange traffic cones blocking the way. It was Thursday about 3:40 p.m.

A construction worker confronted Joseph and an argument turned into a single punch to the head, D.C. police said. Knocked unconscious, Joseph was put on life support.

Joseph, who emigrated from St. Lucia and was an avid gardener who helped his neighbors perfect their plots, died the next day at a hospital. His death has been ruled a homicide.

“It’s a horrific incident,” said the man’s wife, Lisa C. Joseph, 48. “It didn’t have to happen.”

Police said the construction worker, Paul Kenneth Hagans, 36, who lives in Upper Marlboro, Md., was charged with aggravated assault, filed before Joseph had died. Authorities said on Monday that additional charges are pending a review by the U.S. attorney’s office. Hagans’s attorney, John J. Carney, called the incident “a real sad situation” but declined to comment on specifics of the case.

Hagans, who police said had walked away after Joseph fell, surrendered to police hours later and “stated he hit the guy and knows he’s going to jail,” according to the arrest affidavit. He told police that Joseph was “holding a cone and flinched toward him at which time he reacted by punching him,” the affidavit says.

Two witnesses told police that Joseph had nothing in his hands during the argument, according to the affidavit. A third witness said Joseph may have been holding a cellphone and was trying to call 911 when he was struck.

[Man killed in fight over traffic cones]

Hagans described to police seeing Joseph’s eyes roll back as he fell backward to the ground. A Metro transit officer who was driving by saw Joseph, stopped to help and then summoned D.C. police when he was told that Joseph had been struck. Homicide detectives were called immediately because of the severity of the injuries.

Pedro Alfonso, the chairman and chief executive of Dynamic Concepts, where Hagans worked, said it appears that Joseph became frustrated over the work zone disruption, which was to carve out a trench along Rhode Island Avenue in the Eckington neighborhood for updating utilities. Joseph lived in the neighborhood and took daily walks there.

“There was an altercation and words were exchanged,” Alfonso said Monday. “I think it escalated into something like road rage, and a minor incident turned into something tragic.” He said he has fired Hagans.

Joseph also worked for a construction company, the Kady Group, and was one of three workers renovating a building in Bloomingdale, about two miles from where the altercation occurred.

The Kady Group’s owner, Darryl Sulekoiki, said Joseph was trying to park the truck on company property near Rhode Island Avenue and Second Street NE. He said he had given Joseph permission to take the truck to make it easier for him to walk home after the work shift ended at 3 p.m.

“Desmond was an excellent worker and a wonderful person,” Sulekoiki said. “I was almost paralyzed when I heard what happened.”

Lisa Joseph said her husband “probably got agitated” because the cones were in the way of “where he normally parks per instruction of his supervisor.”

Joseph emigrated from the Caribbean island of St. Lucia in 2002 and came to the District via New York. A fellow St. Lucian in Eckington introduced him to Lisa, and they married in 2003 in a ceremony at the D.C. Superior Court. Joseph was a naturalized citizen; he has relatives scattered over Connecticut and New York, where his mother lives. The couple have no children.

“He worked very hard in the construction industry,” Lisa Joseph said, noting that her husband’s daily walks and his routine of playing the lottery numbers at a corner liquor store made him a neighborhood regular.

“As soon as spring started he was the neighborhood landscaper,” his wife said. “He took care of many of his neighbors’ yards. He tried to make their lives beautiful. He made our yard beautiful.” He once surprised the liquor store owner by sharing food with a homeless man on the street.

“He had a very generous heart,” Lisa Joseph said, adding that it was what sold her on her husband. “He came to this country treating everyone the same. Desmond befriended anybody.”

Jennifer Jenkins contributed to this report.