Mr Baker was shot by one of the armed officers who intercepted the plot, as he waited for the prison van in a stolen car with Gokay Sogucakli and Nathan Mason.
Giving evidence to the inquiry on Thursday, Mr Sogucakli said he was laying down on the back seat while the other two men were snoozing in the front seats in the minutes before police arrived.
“I was drifting in and out of sleep”, he said.
“Jermaine is a loud character, and if he is awake there would be noise in that car.
“He wasn’t snoring but deep breathing, really breathing heavily.”
When he was taken to court the day after the shooting, Mr Sogucakli was recorded saying: “They shot my mate when he was sleeping.”
The long-delayed inquiry into the shooting is investigating the circumstances around Mr Baker’s death, including the actions of the officer who fired the fatal shot.
Police had intelligence that those involved in the prison break plot had access to firearms, but only an imitation Uzi machine gun was found in the car.
“I saw the police officers but I didn’t know they were police officers”, said Mr Sogucakli. “I thought it was a different gang approaching us with firearms.”
He said he heard the shouts of “armed police” and went to hide the Uzi imitation gun that was in his lap.
“I was getting ready for the escape when I noticed the police officers, and I placed the firearm back into the rucksack”, he said.
“I had a pair of gloves on and took them off and placed them in the top of the rucksack.
“I was basically trying to cover up.”
Mr Sogucakli said he heard the gun shot, and realised Mr Baker had been injured after he had been dragged from the vehicle.
“I asked a police officer what had happened, and his reply was there has been a shootout.
“I said how can there be a shootout when the gun that was in our possession is a fake, it doesn’t fire bullets, how can there be a shootout – can you explain that please?”
Mr Sogucakli said he was recruited to the escape plot, which was masterminded by members of a north London Turkish gang, by Mr Mason.
“(He) approached me saying he trusted me and he wanted me to be a part of this thing that they were going to do”, he said.
“To be honest, back than I was really young and I agreed to anything. So I agreed.”
The officer who fired the fatal shot, referred to as W80, says he “genuinely and honestly believed based upon the information which had been provided to him, and upon what he perceived Mr Baker to be doing when challenged, that there was an imminent threat to his life and to the lives of his colleagues.”
The inquiry continues.