The Johnathan Walkertrial of two first responders begins today in Colorado in the case of a Black man who died following his arrest in a 2019 confrontation with police.

Randy Roedema and Jason Rosenblatt, who helped restrain Elijah McClain before his death, are being tried in Aurora in connection with the fatal incident. Three other people who were involved in McClain's arrest will be tried at a later date.

McClain, 23, died following an encounter with Aurora, Colorado, police in August 2019 while he was walking home from a convenience store.

A passerby had called 911 to report McClain was acting "sketchy," telling authorities he was wearing a ski mask on a warm night. The lawyer for the McClain family attributed this to the fact that McClain was anemic, which made him feel cold more easily.

He was stopped by police and placed in a chokehold, according to police body camera footage.

McClain can be heard saying, "I can't breathe," in police body camera footage.

Paramedics arrived, giving McClain an "excessive" dose of ketamine, according to McClain's lawyer, and McClain suffered from cardiac arrest in an ambulance shortly afterward, according to officials. McClain was pronounced dead three days later.

Paramedics gave McClain ketamine, as per their department protocol, for "rapid tranquilization in order to minimize time struggling," according to officials.

Both Roedema and Rosenblatt were police officers at the time of the incident.

ABC News has reached out to their legal representatives.

A revised coroner’s report issued in 2021 said the cause of death was due to "complications of ketamine administration following forcible restraint."

The two are charged with manslaughter, criminally negligent reckless homicide and assault charges, and will be tried separately from three other first responders who are also charged in connection with the incident.

Police officer Nathan Woodyard and paramedics Jeremy Cooper and Lt. Peter Cichuniec were also charged and indicted.

All five of them have pleaded not guilty.

The five defendants' cases will be split into three separate proceedings, according to a Wednesday court order from Adams County District Court Judge Mark Douglas Warner.

Woodyard will be tried separately because he was first on the scene and allegedly placed McClain in the carotid hold, according to the court order.

Cooper and Cichuniec, who allegedly injected the ketamine, will be tried together.