The 18-month-old girl was taken into care after she was found to have needles embedded in her arms and body. The needles were discovered during a medical examination. Police investigating the incident said they were treating it as a 'deliberate act'.
The child's parents were questioned by police following the death of their youngest child in January. The child, a month old, was taken to West Middlesex Hospital, west London, suffering from respiratory problems. The child later developed pneumonia and died.
Needles inserted into the baby's skull were later found on X-rays. An inquest ruled the child died from natural causes despite hearing evidence the needles had been pushed there deliberately.
Dr Robert Chapman, the pathologist who found the needles, told the Hammersmith inquest: 'I couldn't determine how long they had been in there. That is a matter for forensics. I simply cannot imagine they got in there by accident. They could not have slipped in easily. They would have needed a good push. My opinion is that it was deliberately done.'
The parents of the dead child were not prosecuted because police had insufficient evidence to charge anyone. The father, from west London, claimed the needles may have been inserted accidentally and could shed no light on how they came to be there.
Detective Superintendent Roland Heming, who led the inquiry into the child's death and is investigating the latest incident, said: 'I do not think it is conceivable that they could have been inserted accidentally. I am treating it as a deliberate act. The needles were found under the skin.
'When I first saw the child she was not in any obvious pain, but I would think that when they were pushed in there would have been pain.' Det Supt Heming said the needles were discovered when doctors examined the girl following the death of her sister. 'At least three needles were found in the arms and trunk of the child when it was X-rayed.'