But the 20 minutes of thump-thump would be too late to save Ashley Smith, who had strangled herself in her segregation cell.
For initial interminably long minutes, guards had simply watched Smith on the floor — wedged between a steel cot and the wall — as she occasionally heaved, her dying gasps audible.
Smith, in a restraint jacket, has her head pressed against the wall, a ligature around her neck. She is mostly motionless.
"It's been long enough for me to take that off," a guard calls through the door.
"Sit up so you can come over here and I can cut it off."
"Ashley. Can you get it off yourself?"
No one tries to get to her, as the video rolls, focused on the seemingly lifeless body, her face turning purple.
At 06:58:06, according to the video, guards dressed in full gear enter the small cell. They don't touch her, but back out amid calls for a nurse.
"'Ashley! Come on. Wake up."
They then go in, give her oxygen.
"Are you getting air in?" "No." "Ashley. Come on. Breathe."
A guard pumps Smith's chest while another gives mouth to mouth.
"Good job, guys. Just keep going," a woman urges.
They finally drag her from the cell as firefighters and paramedics arrive and take over efforts to revive the teen.
One female guard looks totally crestfallen.
"Analyzing rhythm," a mechanical voice sounds. "Do not touch the patient."
"Is she breathing or what? Ashley!" another inmate yells.
About a half-hour later, Smith is finally wheeled out.
The video was taken by Valentino (Rudy) Burnett, a fill-in guard from another institution who had just completed a night shift and he was about to go home.
An all-call for help sounded and he went down to the segregation area, wearing his overcoat, Burnett testified.
"My first question was: What do you guys want me to do?" Burnett said.
"They asked me if I would be video camera operator. They told me they were going to possibly enter Miss Smith's cell."
He was given a camera and he "basically hit record," he said.
"I do what they asked me to do. This was all new to me."
Burnett had been asked to fill in from his regular gig at another institution in Hamilton because he had previously worked at Grand Valley, where he was told staff members were "burning out" and "getting exasperated."
He told the inquest he knew almost nothing about Smith, beyond picking up from other guards that she was a "problematic inmate."
"Will you agree with me, Mr. Burnett, that you in essence videoed somebody's death?" asked Julian Falconer, the Smith family lawyer.
"While I was videotaping her, I saw her chest rising on a number of occasions. I saw her breathing on a number of occasions. As far as I was concerned, I was videotaping a live person."
"Your position today is she wasn't in trouble. I didn't video her death. She didn't need to be saved. Instead of videotaping her, you should have put the camera down and stepped in and saved her life," Falconer persisted.
"No. That's not my job. I was just concerned with doing with I was asked to do."
"I'm going to suggest this has haunted you."
In a perfect world, Burnett said, he would intervene to try to save a life.
"In a correctional world, it's a different story."
Burnett was initially charged with criminal negligence in Smith's death, but the charge was later dropped.
He told lawyer Howard Rubel, who represents the jail guards' union, he could hear breathing in the cell before officers went in.
"I remember somebody saying: 'While she's breathing, we're not supposed to enter the cell'."
Guards disobeyed the directive and went in anyway, Burnett agreed.
On his second fill-in shift there, he said, he had seen guards dragging Smith out of an interview room.
"She had something tied around her neck," he said.
"Did anybody tell you what you should do if you saw that happen?" coroner's counsel Jocelyn Speyer asked.
"No. I was not given any directives."
Smith, 19, of Moncton, N.B., died Oct. 19., 2007 after tying a ligature around her neck, something she had done several times before.
Earlier in the day, an assistant warden at Grand Valley denied authorities had spruced up the death cell before jurors toured last Thursday.
Tony Simoes, who led the tour, described photographs of the cells and what was in them.
Falconer suggested the steel cot in the cell would have been uncomfortable for anyone to sleep on.
"Is sleep deprivation part of (Correctional Service of Canada) punishment?" Falconer asked.
"I cannot comment on that," Simoes responded.
Simoes, in charge of the physical structure of the prison, said he had never slept on one of the cots, and that he didn't know enough to speak to the sleep-deprivation suggestion.
Jurors saw pictures of the segregation exercise yard, a drab, barren concrete slab of about three metres by 10.5 metres surrounded by high razor-wire topped walls.
The rules allow segregation inmates one hour of exercise in the recreation yard, Simoes said.
"The term 'yard' is much like the term 'bed,' isn't it?" Falconer asked.
Smith was admitted directly to the segregation unit on Aug 31, 2007. With the exception of a few hospital visits, she remained in isolation until she choked to death on Oct. 19.
Falconer pressed Simoes to concede there are no special cells for mentally ill inmates.
"There are other spaces in the prison," Simoes said.
"But Ashley never saw those spaces," Falconer rejoined.
Falconer also pointed to photographs that showed clearly visible paint stains and other defects on the cell walls.
"If you're inferring that we painted it just before you came, that's incorrect," Simoes said.
Simoes also said prison policy is that only women guards can monitor surveillance cameras of female inmates.
The hearing continues Tuesday.