Delays by British police meant an opportunity to charge Baby P's mother before his death in north London was missed, a leaked report has revealed.
An investigation into suspicious bruises on the little boy's head and body "drifted" and the six-month limit for bringing a common assault charge passed, the unpublished serious case review into the tragedy found.
The report said the child might have been "more effectively safeguarded" if his mother had been charged, according to BBC London.
Baby P, who cannot be named for legal reasons, was 17 months old when he died at the hands of his mother, her boyfriend and their lodger in August 2007. He had suffered more than 50 injuries despite receiving 60 visits from social workers, doctors and police over an eight-month period.
The little boy came to the attention of the authorities in December 2006 when he was taken to Whittington Hospital in north London with bruises on his head, nose, chest and right shoulder.
Detectives arrested his mother, Baby P was placed on the child protection register, and a file was submitted to the Crown Prosecution Service (CPS). The prosecutors requested further evidence, including medical reports, and a specialist was identified to carry out a review of the child's injuries.
But in March 2007 the detective in charge moved to a different part of the Metropolitan Police without formally handing the case to another officer and the investigation "drifted".
The specialist had no further contact from police until July 2007 despite e-mailing to ask what was happening with the case, the report said. The CPS lost the option of bringing a prosecution for common assault because the six-month period had passed.
The review found that social workers' perceptions of the case could have changed if Baby P's mother had been charged with the offence.
It said: "This might have made it more likely that all the subsequent incidents were reported to the police and that arguably the child might have been more effectively safeguarded."
Other police failings identified in the review include that officers did not photograph Baby P's bruises for a week and kept no detailed notes of conversations with his mother.
Staffing shortages could have been a factor in the mistakes made by police in the case, the BBC said.