A Manhattan bike messenger has been arrested and charged with manslaughter after a confrontation about an elevator at a tony Park Avenue tower left a Merrick man dead Tuesday afternoon, authorities said.

Officers found an unconscious Roger Balan, 58, shortly after 12:10 p.m. outside midtown's 440 Park Ave., where he worked as a porter, the NYPD said. Police said the incident was later "reclassified as a homicide" and arrested the bike messenger, identified as Devon Givens, 35, of 255 Havemeyer St., in the Williamsburg section of Brooklyn, charging him with manslaughter.

An NYPD spokesman said Givens had argued with Balan, of Merrick, over use of the building's elevator. Police said Givens was "unhappy over the fact people using the elevator actually wanted to stop at [their] floors" -- instead of allowing him to go directly to the floor where he was making a delivery. The spokesman said Givens and Balan ended up arguing outside the building.

"There was a physical confrontation," the spokesman said, adding: "It looks like the guy [Givens] who was arrested threw a punch, at which time the victim grabbed his chest." The spokesman said that Givens then continued to assault Balan before fleeing.

The spokesman said it appears Balan may have had a medical episode during the confrontation; police said the medical examiner's office will determine the cause of death.

There was no obvious sign of trauma found when Balan was pronounced dead at Bellevue Hospital Center, police said.

Police said Givens was later tracked down through the messenger service where he works. The service was not named.

With Ellen Yan