A Toronto police constable has been charged with manslaughter and aggravated assault in connection with the death of a 19-year-old in 2021, the province's police watchdog says.

In a news release issued Friday, the provincial Special Investigations Unit (SIU) announced charges had been laid against Const. Calvin Au, in connection with the death of Brampton man Chadd Facey.

"The investigation found that on April 26, 2021, two off-duty Toronto Police Service officers met and interacted with Mr. Facey in Brampton," the news release reads. "Later that day, Mr. Facey was transported to hospital by ambulance where he was subsequently pronounced deceased."

Au is scheduled to appear in court in Brampton on March 2.

The SIU, which investigates the conduct of law enforcement officials where death, serious injury, sexual assault and/or the discharge of a firearm at a person occurred, said it would not make further comment on the investigation as the matter is now before the courts.

In a statement made through the law firm Falconers LLP, Facey's mother Fay Fagan said it has been clear to the family that "some kind of misconduct" had happened in connection with her son's death.

"We are happy to finally see that the officer is being held accountable for his actions," she said.

Facey's obituary said he was a "loving and cherished son, brother, and uncle" who will be "greatly missed by his extended family and friends."

Laywer Peter Brauti, who is representing Au, told CBC News he and his client are "obviously disappointed that the SIU laid these charges," adding they will have no further comment while the matter is before the courts.

Toronto police disciplinary documents lay out what allegedly happened during the incident. Both Au and Const. Gurmakh Benning are facing separate discipline charges stemming from a failure to report their connection to what happened, but Benning has not been criminally charged. The disciplinary charges have not yet been tested at the police tribunal.

Toronto police say Au, 33, has been with the force for eight and a half years, and was most recently assigned to 55 Division. He "will be immediately suspended per the Police Services Act," Const. Cindy Chung said in an email.

According to tribunal documents, on that day in April, Au and Benning were both off duty when they travelled to Brampton for a meeting with a man who had been advertising an Apple watch for sale on Kijiji.

Right after the transaction, Au realized the watch was counterfeit. That's when, the documents allege, Benning drove his car in the direction Facey was last seen running, eventually catching up to him. Benning said the watch was fake and he wanted his money back, but Facey continued to run, according to the tribunal.

Au then got out of the vehicle and ran after Facey, eventually catching up with him. Benning told Facey to give him back his money, and reached for it while Au "took the male to the ground," the documents say.

Au was "engaged in a struggle" with Facey while they were on the ground, with the officer trying to "maintain physical control" as Facey tried to get up, according to the tribunal. A second man then approached the area and both officers ran to their car and drove away, the documents say.

According to tribunal documents related to Benning's disciplinary case, he had placed a call to 911 indicating a "Kijiji deal that had gone bad," but he did not identify himself as a police officer during the call, and later advised the operator that the matter was "resolved."

Shortly after the incident, Facey was taken to hospital by paramedics, where he later died.

According to the police tribunal documents, Peel police later got a call from Brampton Civic Hospital in regards to Facey's death, and so the criminal investigative bureau launched an investigation.

Later, through an examination of Facey's phone records, investigators were able to discern that he had met up with Benning on the afternoon of April 26. Benning told Peel investigators about what had happened, and also said Au was there when the incident took place.

"Neither you nor PC Benning notified anyone with the Toronto Police Service about your involvement in the incident in Brampton," the documents linked to Au's tribunal hearings allege. "Your actions were discovered as a result of another Police Service's investigation."

Peel Regional Police first notified Toronto police about the incident on Aug. 24 — four months after it took place. The tribunal says both Toronto police officers did not abide by the force's standards, and their actions resulted in an SIU investigation.

"In doing so, you committed misconduct in that you did act in a disorderly manner or in a manner prejudicial to discipline or likely to bring discredit upon the reputation of the Toronto Police Service," the documents read.

The police tribunal is alleging both officers neglected their duties in that they did not tell the 911 operator that they were police officers, didn't notify Peel police despite the incident happening in that service's jurisdiction, didn't tell one of their own supervisors about what happened, and didn't notify Toronto police once they became aware of the active criminal investigation.

Const. Chung, a Toronto police media officer, said the force "immediately" notified the SIU when it heard about the incident. At the conclusion of the criminal proceedings, Toronto police will complete two additional, separate disciplinary investigations into the officer's conduct, she said.

When asked for comment, Toronto Police Association president Jon Reid said in a statement that "any death is tragic and impacts everyone involved."

Reid, whose association represents Toronto police officers, said as the matter is now before the courts, he would not be commenting any further.

"We will continue to ensure our member is treated fairly throughout the process," he said.