A woman remains in custody after being arrested on suspicion of preventing a lawful burial by detectives investigating the disappearance of a baby more than 11 years ago.
The investigation into the missing child, born in Barnet in 2004, was sparked by requests from local officers and the child abuse investigation team following a case review into the death of another child at an address in Barnet in 2015.
The Metropolitan Police said the case had been referred to its Directorate of Professional Standards (DPS) and also to the Independent Police Complaints Commission (IPCC).
A 50-year-old woman was arrested after officers attended a home in Fryent Crescent, West Hendon, north London at 7am on Monday May 30, and a 31-year-old woman was detained in Luton, Bedfordshire later that day .
Both were bailed to mid-July after being taken to a south London police station.
Human remains thought to be those of a child, who police have not identified, were found during a search of the address on Tuesday May 31.
On Wednesday, detectives rearrested the two women, as well as a 52-year-old man, on suspicion of preventing a lawful and decent burial.
The older woman has been bailed along with the man to mid-July, while the younger woman remains in police custody.
A post-mortem examination on the remains at Great Ormond Street Hospital was inconclusive on the cause of death.
A Metropolitan Police spokesman said: "Further tests will be undertaken and this could take a number of weeks.
"We will not speculate on the identity of the child until all further tests have concluded.
"Given the circumstances which led to the launch of this investigation, officers from the Directorate of Professional Standards (DPS) have been informed. A referral to the Independent Police Complaints Commission (IPCC) has been made.
"Detectives continue to investigate and are liaising with partner agencies."
Anyone with information should contact the homicide and major crime command (HMCC) incident room on 020 8785 8099.