A young mother believed to have killed her two children suffered badly with depression following a difficult relationship with her boys' 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 of Ms 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.
Ms 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".
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."
Devon and Cornwall Police 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."