It took guards at WA's notorious Unit 18 youth detention facility 16 minutes to check on Cleveland Dodd after the teenager warned them he would attempt to take his own life, the ABC reports.

On Monday, alleged details of the timeline surrounding the 16-year-old's final moments at Casuarina maximum security adult prison's "youth wing" have come to light after ABC 'obtained access to information and sighted documents' related to the evening last month.

Cleveland is the first child to die in WA youth detention in the state's history.

According to the ABC report, he told officers "I'm hanging myself" before another officer conducting cell checks, allegedly unaware of his call, spoke with him through his cell door for about 20 seconds.

Within minutes of his first call, Cleveland contacted officers through the intercom a second time with a similar warning.

13 minutes went by between a physical check on Cleveland and when he was found unresponsive.

The same officer conducting the cell checks was unable to immediately enter his cell and first had to retrieve keys from the duty manager at the control centre.

Night staff were not issued with radios, meaning the officer who found Cleveland is understood to have not been aware of his suicide threats and could not call a 'code red' to alert nurses from across the prison.

According to the ABC, Cleveland's cell had not been monitored over CCTV surveillance for close to 12 hours after the camera had been covered by a strip of toilet paper "for all but a brief few seconds after midnight".

Cleveland's suicidal behaviour was not detailed on official records on the night.

Safety checks of detainees at Unit 18 are meant to take place each 15 minutes either in person or via CCTV.

According to the ABC, Cleveland's records had been filed up, seemingly in advance, until 6am in the morning - more than three hours after he left in an ambulance in a critical condition.

The detainee in the cell next to Cleveland's had called central officers over the intercom to alert them to the situation.

The central officer said he'll "get someone up there to chat" in response.

Around 16 minutes elapsed between Cleveland first threatening to take his own life and an officer entering his cell.

CPR then began.

A faint pulse was not detected until around 30 minutes later - after ambulance officers took over.

Cleveland had only been removed from the 'at-risk list' days earlier, after self-harming the previous month.

According to the ABC, his suicide attempt on the same day of his final court appearance.

Cleveland had unsuccessfully tried to phone his mother on three occasions.

The air vent he used to take his own life had been damaged for several weeks, meaning the cell should not have been occupied on the night, in further details reported by ABC.

A contractor had tried to organise its replacement several times, and arrived to make the repair the day prior to Cleveland self-harming. It is not publicly known why the repair was not made on that day.

National Indigenous Times contacted WA Minister for Corrective Services Paul Papalia for comment.