An elderly Queensland mother of 11 children has been charged with murdering her autistic son more than 50-years-ago.
Peter John Enright's parents, Maureen and Michael Enright, didn't report him missing when he disappeared in 1968 or 1969 aged three or four years old.
But police allege his mother Maureen, now 76, murdered him at their Brisbane home and may have had a hand in burying him in the yard.
"Time causes problems but ... it's been a fascinating case," Detective Inspector Damien Hansen told reporters at the crime scene.
"There were 11 children in the family, he was number 4, a lot of those siblings were unaware (but) they'd heard stories.
"They were aware Peter existed."
Detectives took the 76 year old into custody on Wednesday evening and charged her with murder after interviewing the surviving family.
Bone experts and forensic officers on Thursday started searching for Peter's remains at the Inala home where the family lived from 1966.
They've removed decades' of debris from under the house and are using ground-penetrating radar to scan beneath the earth.
Peter was born June 17, 1965. His father Michael died in 2018.
"We're searching for a body. We're optimistic at this stage but that will be dependent on a lot of environmental factors ... time and acidity of soils," Det Insp Hansen said.
Homicide detectives started the murder investigation after receiving a tip-off in August about Peter's disappearance and suspected death.
"A person came forward with the information," Det Insp Hansen said.
Detectives have urged anyone who lived on Polaris Street in Inala in the 1960s and 70s to contact police if they have information.
"They were quite well known. Some of the neighbours have been here for a long time too," Det Insp Hansen said.
Ms Enright appeared in Richmond Magistrates Court on Thursday.
Her case will be re-mentioned on December 11.
Australian Associated Press