[What you need to know to start the day: Get New York Today in your inbox.]

A police commander in Staten Island received text messages from one of his officers in July 2014, informing him that a man identified as Eric Garner had been arrested, and was “most likely DOA” after he had been wrestled to the ground.

“Not a big deal,” the lieutenant replied. “We were effecting a lawful arrest.”

Audible gasps were heard as the texts were read aloud on Thursday during a police disciplinary hearing for Officer Daniel Pantaleo. He is accused of recklessly using a chokehold that led to Mr. Garner’s death after he was detained on the suspicion that he was selling untaxed cigarettes.

The texts and testimony provided unsettling new details in one of the most wrenching cases of suspected police misconduct in New York.

Mr. Garner’s dying words “I can’t breathe” — repeated 11 times — set off protests around the country and became a powerful slogan for the Black Lives Matter movement.