Here's the account from Wikipedia (which is fully footnoted and referenced):
Vázquez said that Penny asked other riders to call the police while he had the chokehold.[15] Penny had learned the technique for restraint in basic training.[25][26] Another witness said that at some point during the chokehold, Penny relaxed his grip on Neely, and Neely coughed up a wad of blood and mucus.[27] The same witness noted that nobody on the train car was telling Penny to stop his chokehold, and that some passengers expressed hostile statements toward Neely and support for Penny's actions.[27]
At 2:29 p.m., a passenger on the train warned that Neely had defecated on himself, a sign that he may be dying, saying, "You don't want to catch a murder charge. You got a hell of a chokehold, man."[19][28] One of the other men restraining Neely responded, saying that the excrement on Neely's pants was old. He also responded to the warning by saying that Penny had stopped "squeezing" Neely's neck.[28][29]
About 50 seconds after Neely became motionless, Penny and one man who was still restraining Neely's arms released their hold on him.[24][30] Shortly thereafter, a man named Johnny Grima can be seen in the video saying, "Don't put him on his back though, man. He might choke on his own spit."[31] Penny placed Neely on his side, into a recovery position.[28] Grima said that he put water on Neely's forehead, but was told to stop by Penny.[32] Other passengers also checked on him, including an onlooker who warned Penny about killing Neely, who said, "He's all right. He ain't gonna die."[33][19]
https://en.wikipedia.org/wiki/Killing_of_Jordan_Neely