This information is the only fresh new lead for detectives trying to determine what caused the accident that claimed the life of 38-year-old mother of three Narissa Fox and hospitalised her three young daughters.

The January 19 accident saw Ms Fox’s Nissan Pulsar leave the road, collide with an embankment and roll before hitting a tree around 2.20pm 20 kilometres south-east of Young on the Moppity Road.

Ms Fox remained trapped in the wreckage but her daughters - aged nine, 12 and 15 - were able to free themselves and flag down a passing car for help.

Their mother was airlifted to Canberra Hospital but died some hours later.

The 12-year-old suffered leg and shoulder fractures and was also airlifted to Canberra Hospital while the nine-year-old and 15-year-old were transported to hospital by road after suffering minor injuries.

The family were in the process of moving from Sydney to Young and were temporarily living at Young Caravan Park.

On Tuesday, Inspector Ashley Holmes told media the handwritten letter addressed to him indicating there was a black vehicle involved had been sent to Young Police Station two months after the accident.

“We’re appealing for the person who wrote that letter to come forward, even if the information they gave us was third-hand, we need to speak to them - obviously these three young daughters need to have closure on what happened - they don’t need to go through life not knowing what happened,” he said.

“There was no physical evidence to indicate the involvement of a black car, just one of the daughters and this letter.

“We’re pleading for that person to come forward, the police investigators have exhausted every line of enquiry and we really need that person to come forward to advance the investigation,” he said.

Inspector Holmes said there were no clues as to where the letter was posted but confirmed the black vehicle had some sort of roof racks on top, was displaying a p-plate and was being driven by a young male.

Callers are urged to contact Cootamundra Police Station on 6942 0099 or Crime Stoppers on 1800 333 000. 

Callers to Crime Stoppers can remain anonymous and a reward of up to $1000 is payable for information which leads to an arrest.

“These children need answers,” Ms Fox’s mother Jennifer Smidt told media at the Young Police Station.

She speaks of course of her three grandchildren - Chloe 9, Elly 13 and Mikaila 15 - who lost their mother in the fatal crash.

The same three children who go to bed each night with their mother’s clothing to capture her scent.

“It’s hard because they’ve lost their mother and they’re not coping that well - they’ve put on a good face now,” she said.

Now based in Young, the family of four have settled into as normal a routine as possible as the children come to terms with the loss of their mother. 

Here they are nestled among a supportive Young community and family members - like Jennifer’s brother Glenn Perkins of Thuddungra, also present at the press conference.

But there are still scars and many questions.

“The children I suppose are angry, they just want their mother’s name cleared - everyone said she had this accident and it was her fault and they don’t want her to get the blame - that’s how they’re feeling,” she said.

It was young Chloe who alerted police to the presence of a black car at the scene of the accident back in February.

“She was very insistent,” Jennifer said,

“It was the same story about this black car over and over and over again and we tried to draw it out of her - was there some way you made a mistake - but no, she hasn’t changed her story and she was nine years old - a very sensible nine-year-old - but she never changed her story.”

“She remembers a black car coming towards the car on the wrong side of the road and she remembers mummy swinging on the steering wheel to try and miss the black car and then she remembers them starting to turn and when it stopped she remembered looking out the back window and seeing this man on the side of the road - he got out of his car and looked down on them on the side of the road, and got back in his car and drove off.”

The man, according to Chloe was dressed entirely in black.

Jennifer says she hopes someone comes forward to help give the family closure.

“I just want them to come forward, I really don’t have this great need for revenge - just want him to come forward. I know he’s probably got to go through all sorts of things legally but I don’t want bad things for him if he’s young, I don’t want his life ruined, really I just want him to come forward - that’s all.”