A woman who was stabbed to death with her young son in Derbyshire was three months pregnant, police have revealed.
Rachael Slack, 38, and 23-month-old Auden died from knife wounds after the incident in Holbrook, near Belper, on Wednesday.
Friends said she had met a new boyfriend after the breakdown of her relationship with Auden's father, 44-year-old Andrew Cairns, from Ripley.
Mr Cairns was also found dead from knife injuries at the house.
Derbyshire Police said they were not looking for anyone else in connection with the deaths.
The Independent Police Complaints Commission (IPCC) has confirmed it would investigate police contact with Mr Cairns a week before the deaths.
Mr Cairns was detained by police on 26 May under the Mental Health Act. He then took a mental health assessment and was allowed to return home to Ripley.
The IPCC has confirmed he was then arrested on 27 May on suspicion of making threats to kill and bailed the following day with conditions not to contact Ms Slack.
IPCC Commissioner, Amerdeep Somal, said: "These deaths have understandably shocked and concerned the community.
"It is right that we undertake a thorough and independent investigation into the actions of the police and others to establish whether or not any more could reasonably have been done to prevent them."
It has emerged that Mr Cairns had been a mental health patient in Derbyshire for about a year.
A spokesperson for the Derbyshire Mental Health Services NHS Trust said: "I can confirm that the man concerned was a service user of our organisation.
"We have launched an immediate internal inquiry looking at the circumstances surrounding his contact with our organisation and we continue to help Derbyshire Police with their criminal investigation."
Friends of Ms Slack said Mr Cairns had been making threats in the weeks before the killings.
They added that she had gone to live in Spain with Mr Cairns but had returned and struck up a new relationship.
It is thought Ms Slack met Mr Cairns in Australia while she was working with stockbroker Adam Wilson.
Mr Wilson said: "Rachael was a victim really of her own big heart. Andrew had problems with depression and was a difficult and curt character when I had met him.
"Most people would have just turned their back on him but that wasn't Rachael's way. She would have just tried to help him and it turned out to have tragic consequences."
A neighbour heard Ms Slack screaming for help from a window, but by the time emergency services arrived she and Mr Cairns were dead. Auden was rushed to hospital but died of his injuries.