Further tests are being carried out on the bodies of a man, his ex-partner and their children after the family were found dead in Leicester.
Aram Abdul Razaq Aziz, 32, was found at Watermead Country Park on Friday.
His former partner Joy Small, 24, their son Aubarr, three, and daughter Chanarra, two, were found on Saturday at a flat two miles away.
Post-mortem tests have been carried out but more tests were required before the causes of the deaths could be released.
The Leicestershire force said it was not looking for anyone in connection with the deaths.
Officers have confirmed they have had previous contact with the family, and discussions have been held with the Independent Police Complaints Commission (IPCC) as to whether the case should be referred to it.
A police spokesman said: "It is the force's procedure to carry out a full and thorough review into all previous involvement with the family to enable us to have a full understanding of the history.
"This together with the information gathered from the investigation will then be provided to the HM Coroner and will form part of the inquest into the deaths."
He added: "The investigation into the deaths continues and officers have been carrying out house-to-house enquiries.
"The forensic examination of the flat has now been completed. Specialist officers are supporting family members at this extremely difficult time."
Friends and neighbours have expressed their shock at the deaths.
One neighbour, Jennie Bland, 27, described Ms Small as "such a good woman".
She said: "She was a fantastic mum. She would have died for those children."
Floral tributes have been placed outside the flats on Jersey Road along with a pink and blue teddy bear.