Officers discovered 16-year-old Cleveland Dodd in the Unit 18 youth detention facility at Perth's Casuarina Prison on October 12, after he contacted them through the intercom.
He was taken to a Perth hospital in a critical condition, where he later died.
The Department of Justice confirmed the officer had been suspended from duty pending the outcome of an inquiry.
"The department won't comment on specific matters under investigation," a spokesperson said on Wednesday.
The teen's death is being investigated by the Department of Justice and the coroner.
The Corruption and Crime Commission has also begun an investigation following allegations of serious misconduct.
Cleveland was the first child to die in WA juvenile detention in the state's history.
The area where he was found, Unit 18, opened in July 2022 to house the most challenging juvenile offenders after major riots at Banksia Hill Juvenile Detention Centre.
Both facilities have been plagued by high rates of self-harm incidents and detainees being placed into prolonged lockdowns.
Premier Roger Cook said the situation was "not good enough".
"We've let that young detainee down and as a result of that we need to continue to learn and we need to improve," Mr Cook said on Tuesday.
He didn't want youths to be detained in the maximum-security men's prison but it was necessary due to the riots at Banksia Hill, he said
The opposition, along with advocates, have called on the government to close Unit 18.
17°C