Police investigating the death of a two-year-old girl who was submerged in a Welsh river after the car she was in rolled down a slipway have confirmed that the vehicle was not stolen.

A detailed inspection of the car – a recently purchased silver Mini – will be a crucial part of the investigation into the death of Kiara Moore.

Dyfed-Powys police also said they were looking at malicious comments made on the internet after the incident on Monday.

Initially Kiara’s parents, Kim Rowlands and Jet Moore, believed the car had been stolen after it vanished with Kiara inside from near a slipway leading to the river Teifi in Cardigan, west Wales.

The police were alerted and the family frantically posted appeals for help on social media. Eventually the car was found 150 metres downstream and Kiera was pulled out but could not be saved.

On Wednesday Dyfed-Powys police said they were still working to fully understand the circumstances. A force spokeswoman said: “Examination of the vehicle will form part of these enquiries. We can also confirm that the vehicle had not been stolen.”

After the incident, there was a slew of derogatory comments on social media, much of it aimed at Kiara’s mother. In response, police warned they could act against the trolls.

The force tweeted: “We ask people to think very carefully before posting and not to speculate on circumstances of incidents. We are aware of comments on threads across social media which are being looked at. Posts considered to be malicious will be recorded and police action may follow.”

Describing the circumstances of Kiara’s disappearance, her father, who runs an outdoor adventure company close to the spot, said on Facebook: “They got in the car to go home. Sat on bank card which snapped and needed money to get home etc.

“Went back to the office to get money from the desk and came back to no car. Looked in the river. No signs. So we thought she and the car had been taken.”

Her mother wrote: “Mummy loves you baby girl and I’m so sorry. I will have to live with the guilt for the rest of my life.”