Mistakes made by police and other agencies "probably" contributed to the death of a baby boy who was killed by his violent father, an inquest ruled.
Four-month-old Alfie Gildea died after being found with head injuries at his home in Trafford, Greater Manchester, in September 2018.
His father Samuel Gildea was later jailed for 19 years for manslaughter.
The inquest heard police repeatedly failed to "appropriately" assess the risk posed by Gildea.
Greater Manchester Police said the force had since revised its domestic abuse policy.
In court Gildea admitted causing Alfie's death in an "act of deliberate and unlawful violence which involved rigorous and violent shaking".
He was found by his mother and died two days later at the Royal Manchester Children's Hospital.
The inquest heard Gildea had a history of domestic abuse and should have been considered by GMP as a "serious and serial domestic abuse perpetrator".
Blood samples taken from Gildea the day after his son's death showed traces of cocaine and cannabis in his system, consistent with recent use.
Officers were called to a previous domestic incident at the home in July 2018 but failed to correctly assess the risk or recognise Gildea's "coercive or controlling behaviour", the inquest heard.
GMP passed information on to Trafford Council's Children's Services, but they failed to review all the material and the case was closed without "effective communication" with other agencies.
'Serial domestic abuser'
The Health Visitor Service was also made aware of the incident but did not correctly assess the level of risk or engage with Alfie's mother.
Police were called to another incident a month later and officers again did not recognise Gildea as a serial domestic abuser, the hearing was told.
Social workers and health visitors were again notified but again failed to realise the level of risk.
Coroner Alison Much said: "The failure by GMP, Children's Services and the Health Visitor Service to share information effectively, to appropriately assess the level of risk and effectively communicate the level of risk to Alfie's mother after the incident on 10 July 2018 probably contributed to Alfie's death".
A GMP spokesman said the force was considering procedural changes.
He said: "We recognise that reports of domestic abuse are often extremely complex and must involve the expertise of specialists from partner agencies from the very outset in order to provide the best support possible."
Trafford Council did not respond to a request for a comment.