A disturbing video the New York Daily News posted on its website Friday shows a plain-clothes police officer choking a Staten Island man, who later died.

The video, captured by a civilian bystander, begins with 43-year-old Eric Garner telling the cops he “didn’t do shit,” and that he was “minding his business.” The tension escalates until one cop takes the estimated 400-pound Garner and puts him in a chokehold. Soon after — horrifyingly — Garner tells the cops, “I can’t breathe!” The father of six with asthma died of cardiac arrest at Richmond University Medical Center, according to the NYPD.

Cops had accused Garner of illegally selling loosie cigarettes; Garner’s widow told the News there were none found on him or in his car. The confrontation continues until Garner’s brought to the ground and looks motionless.

There were multiple witnesses using smartphones to record the assault and in the video it appears a police detective pushes back the videographer when it becomes obvious that Garner is in serious distress. “Back up this way, everyone now back up,” he says. “In your house or that way. You had your chance.” As we reported earlier, attorney Norman Siegel recently filed a lawsuit in defense of citizens’ rights to record arrests.

Staten Island District Attorney Daniel Donovan has launched an investigation into Garner’s death. At a press conference at City Hall on Friday, Mayor Bill de Blasio said he was saddened by the video.

“It was very troubling,” de Blasio told reporters. “I watched it the same way a family member would watch it. It was very sad.”