A young mother believed to have killed her two children suffered badly with depression following a difficult relationship with her boy's father, neighbours have claimed.
Police began investigating after the bodies of Katherine Hooper, 24, and her five-year-old son Joshua Patterson were found at the bottom of a 100ft cliff in Dartmoor National Park on Friday.
Officers later discovered the body Hooper's two-year-old son Samuel Patterson after searching her home in Paignton, Devon.
Detectives said they are not looking for anyone else in connection with the incident - but confirmed all three had been known to various welfare agencies and a Serious Case Review would also be launched as well.
Hooper's estranged partner Neil Patterson, 52, said he had been left devastated by the tragedy.
But her next-door neighbour Johnathan Grant, 28, told the Daily Telegraph that the two had a fractious relationship - which culminated in a court case following an "almighty bust up".
In April, Patterson appeared before magistrates where he pleaded not guilty to assault by beating.
Mr Grant was reported as saying: "One night in May they got into a huge argument where there was an almighty bust up.
"Since then she has suffered badly with depression.
"Samuel was meant to be starting his first day at the local nursery yesterday.
"The boys were lovely and played with my girls. Kat had lived there for three years. It is sick, utterly sick what has happened."
Grant added that following the breakdown of her relationship, she became very anxious and became too unwell to carry on her job at a local hotel.
Last May, police launched a major search and rescue operation after Ms Hooper suddenly disappeared with her two children.
After fears for their safety grew, officers called on the Dartmoor Search and Rescue Team to help with the search.
Twenty-four hours later, Hooper was found reportedly covered in mud and suffering from dehydration.
She was then taken to hospital while her two sons were taken into care.
Two weeks ago, Hooper and her two sons moved back into their home in Dukes Close.
Then just before midday on Friday, the unthinkable happened.
Foreign tourists reported seeing Hooper standing on top of a granite outcrop in Haytor - with a child on her back or shoulders and suggested she may have jumped.
Scores of police, paramedics and search and rescue teams in 20 vehicles then rushed to the scene - where Hooper and her young son were found lying at the bottom of the rock face.
Air ambulances were dispatched, but the woman and the child both died shortly after the fall at 11.50am.
The deaths prompted police to carry out a search of their home and - upon forcing open the property's front door - they found little Samuel dead in his bed.
Devon and Cornwall Police's Major Crime Investigation Team confirmed it had launched a murder investigation.
Detective Superintendent Paul Burgan said: "We are keeping an open mind about all three deaths, but at this stage we are not looking for anyone else in connection with the incident.
"We are keen to speak to anyone who may have any information or might have been in the Haytor area earlier today, Friday."
Police also confirmed that while no formal identification had taken place, the deceased were "believed to be Katherine Hooper, Josh Patterson, aged five years and Sam Patterson aged two years".
A spokesman added: "We can confirm the family were subject of Safeguarding Partnership Intervention prior to their untimely deaths.
"This investigation will now be referred to a Serious Case Review process as per national good practice.
"The partner agencies are assisting police with the investigation and further detail cannot be released at this time."
A spokesman also said family liaison officers had been appointed to assist the immediate family before issuing a statement from Mr Patterson.
It said: "On the Friday evening I heard the devastating news the three most important and cherished people in my life had been taken from me.
"I would gratefully appreciate for me and my family to be left alone to come to terms with this devastating loss and to grieve in peace."
In the meantime, detectives say they want to hear from anyone who saw Ms Hooper or her two children in the days running up to their deaths. Those able to assist officers should contact Devon and Cornwall Police via the 101 telephone number quoting log number 316 of 120713.
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