The two Ottawa police officers under investigation after the death of an Ottawa man following an arrest have been identified as Const. Daniel Montsion and Const. Dave Weir.

Abdirahman Abdi, a 37-year-old with mental health issues, was taken to hospital on Sunday after what witnesses described as a violent arrest. He died on Monday.

Abdirahman Abdi, 37, a Somali-Canadian with mental health issues, moved to Canada with his family eight years ago. He died after an arrest by police on Sunday morning. (Abdi family) Ontario's police watchdog, the Special Investigations Unit, is handling the investigation into Abdi's death, which could take months. An autopsy was scheduled for Tuesday.

The SIU said the investigation is focusing on two police officers and that it intends to interview five witness officers.

Multiple sources have confirmed to CBC News that the two officers under investigation are Weir, a patrol officer, and Montsion, who usually apprehends gang members as a member of the direct action response team (DART) but on Sunday was assisting on patrol.

Video shows officers after arrest

Montsion can be seen kneeling to the right of the bloodied and handcuffed Abdi in a video posted on YouTube on Tuesday, two days after the arrest. Weir is the officer kneeling by Abdi's head.

Police kneel and stand by the bloodied and handcuffed Abdirahman Abdi as people inside an apartment building cry out. Warning, some people may find this video disturbing. 1:51

The one-minute 51-second video, taken from the lobby of 55 Hilda St., doesn't show the altercation, but instead shows Montsion and Weir kneeling by Abdi's body while three officers stand by the door to the building.

It's not clear who took the video or exactly when it was recorded. It appears to be after Abdi's arrest but before the arrival of paramedics.

Several people inside can be heard wailing and screaming.

A man's voice can be heard identifying himself as the superintendent of the building and saying to police, "This is the family. This is the family."

Another man, speaking in Somali, can also be heard saying "Take mom away, take her out of here. Take mom."

A video that had been previously posted to YouTube shows paramedics arriving and performing CPR on Abdi. Montsion can be seen in that video assisting paramedics.

Paramedics then took Abdi to the hospital, where he was listed in critical condition.

Abdi was pronounced dead at 3:17 p.m. Monday. A neighbour speaking on Monday for the family said doctors had told them Abdi was already dead when he arrived in hospital.

2 officers seen hitting Abdi

​Eyewitnesses to Abdi's arrest described it as a violent altercation.

Police had been called to a coffee shop in the city's Hintonburg neighbourhood at about 9:30 a.m. ET after reports someone was groping people.

One officer located and pursued Abdi to his apartment building at 55 Hilda St.

Ross McGhie and his partner were returning from a run when they saw a police officer pursuing Abdirahman Abdi on Sunday. (CBC) Ross McGhie and his partner said they were returning home when they saw the first officer trying to prevent Abdi from entering his building.

McGhie said the officer used his baton to strike Abdi in the legs, arms and upper body while shouting at Abdi to comply.

A second officer arrived at the scene in a police cruiser, ran out of the car and jumped into the altercation, delivering what McGhie described as "a number of very heavy blows to the head and face."

McGhie on Tuesday said the second officer was wearing a DART vest and, when shown a still from the YouTube video, identified him as Montsion.

'They wanted him dead'

Zeinab Abdallah, an elderly Somali woman who lives in the building, said she was leaving at the same time Abdi and the first officer were running toward it.

Speaking in Somali, she told CBC's Idil Mussa that Abdi called to her, "Sister, protect me from them. Zeinab, help me. Zeinab, help me."

"As I looked one side, I was shocked, since my looking to that direction coincided with the policeman hitting him with a stick, the very moment he held the door trying to get inside," she told CBC News.

"He was fleeing the policeman and was trying to go inside the building. Having received the blow, he turned back and grabbed the policeman, they grabbed each other, two strong men, the policeman tackled him and threw him to the ground, hitting him repeatedly.

People have left candles, flowers, a Black Lives Matter sign and a 'Love' sign at the entrance to 55 Hilda St., where Abdirahman Abdi was arrested on Sunday. (Giacomo Panico/CBC) "And there was this cut here and his blood run on the ground. Then he started beating him hard with the object he was carrying, and when he did so, I pleaded with him to stop the assault, informing him that the man was mentally ill.

"I pleaded with him, 'Please don't beat him, please, he can't listen, he don't care.' The other policeman joined him, they did whatever they wanted with him until he became incapacitated.

"I have never seen anything similar to the way they beat him with such malice, animosity and hostility. They simply didn't want him alive, they wanted him dead," she said.

The SIU is in possession of the building's security video footage of the arrest, CBC has learned.

The head of the police union said police were responding to a "violent incident," and that they had to contain it.

"The officers were experiencing a male that was assaultive in behaviour," said Matt Skof. "So they are required, they're bound to react to that, they have to react to that, they have to contain that."

Group calls for thorough investigation

The National Council of Canadian Muslims released a statement Tuesday calling for a thorough investigation of the arrest.

"The community we're hearing from here in Ottawa — and across the country — want answers. So it's really important that the SIU conducts the investigation thoroughly, transparently," said NCCM spokesperson Amira Elghawaby.

A public memorial for Abdi will be held at Somerset Square Park, between Wellington Street West and Somerset Street West at Spadina Avenue, on Tuesday at 8:30 p.m. ET.

A funeral is tentatively scheduled to take place at the Ottawa Mosque, though the day and time is still to be determined.

Translation of witness account

Here is the full translation of the account of Zeinab Abdallah, an elderly Somali woman who told CBC News she witnessed the arrest. Translation by Abdullahi Bogor from Somali to English.

"The man, the young man, was running toward the building at the same time I was leaving it. He was carrying a black plastic object. He called out to me and said 'Sister, protect me from them. Zeinab, help me. Zeinab, help me.'

"And, when I looked, it was a policeman chasing him while he was running toward the building. He was trying to get into the building since he was being chased by them. I didn't know what happened. I know that this man has mental illness and was running toward the building he was running at that moment.

"As I looked one side, I was shocked, since my looking to that direction coincided with the policeman hitting him with a stick, the very moment he held the door trying to get inside. He was fleeing the policeman and was trying to go inside the building.

"Having received the blow, he turned back and grabbed the policeman, they grabbed each other, two strong men, the policeman tackled him and threw him to the ground hitting him repeatedly and there was this cut here and his blood run on the ground then he started beating him hard with the object he was carrying and when he did so, I pleaded with him to stop the assault informing him that the man was mentally ill.

"I pleaded with him 'please don't beat him, please, he can't listen, he don't care.' The other policeman joined him, they did whatever they wanted with him until he became incapacitated."

(voices from the background to which she answers)

"Auntie, in my entire life, I have never seen anything similar to the way they beat him with such malice, animosity and hostility. They simply didn't want him alive, they wanted him dead."

(voices from the background to which she answers)

"They hit him with their knees, the camera will show that. They beat him with everything. They kicked him. They did everything they wanted with him. They beat him. The strong man who not long ago was running, was taken in an ambulance barely alive."

(voices from the background to which she answers)

"When my son saw me, he got scared and urged me to leave the area but I told him I was going nowhere. He didn't know exactly what happened. If only my son brought his camera earlier. He brought it later on."