Darren King, a member of the public who had an appointment with Sir David after Mr Ali, can be seen showing the officers where in the building the suspect – who was still brandishing a knife – was standing.
Giving evidence on Wednesday, Mr King told the court the defendant had refused to put down the knife, telling him: “I want to be shot, I want to die, I want to be a hero.”
In the body-worn footage, the officers can be heard discussing that back-up, including officers who were armed with Tasers, was two minutes away.
The officers repeatedly shout at the suspect to drop the knife, with one of them adding: “It’s only going to go one way. Please drop that knife.”
The officers – who were not wearing stab vests – then rush the suspect, forcing him to the ground before kneeling on him and cuffing his hands behind his back.
During a brief verbal exchange, Mr Ali is heard to say he was “prepared to die”, before asking the officers to put his glasses back on his face.
As he is arrested and read his rights, one of the officers replies: “Mate, that’s not our concern.”
The suspect who had been on the phone to his sister at the time, can also be heard saying: “Don’t worry. The police got me. They’re not gonna shoot.”
Paramedics tried to revive Sir David, but he was declared dead at 1.10pm. The father of five had suffered 23 knife wounds, including four to his chest.
Jurors were also shown still images of Mr Ali shortly after he had been arrested on suspicion of murder, appearing to look relaxed and calm.