Francecca Hardwick, 18, and her mother Fiona Pilkington, whose bodies were found in a burning car in 2007. Photograph: Leicestershire police/PA

Police were called 13 times about a family tormented by a gang of youths the year the mother killed herself and her severely disabled daughter but officers did not recognise their vulnerability and never identified the incidents as hate crimes, an inquest heard today.

The bodies of Fiona Pilkington, 38, and her 18-year-old daughter, Francecca Hardwick, known as Frankie, were found burnt beyond recognition in her Austin Maestro in a layby in Leicestershire in October 2007.

That year police had repeatedly been called to reports of the family being under siege in their home in Barwell, near Hinckley, with youths outside throwing stones and shouting abuse and obscenities, the hearing at Loughborough town hall was told.

Frankie had severe learning difficulties, was doubly incontinent and could not be left on her own. Her brother Anthony, now 19, is severely dyslexic and was frequently bullied, and Pilkington was described as shy, timid and vulnerable.

Chris Tew, former assistant chief constable of Leicestershire police, admitted the biggest problem in the policing of the case had been a failure to link the incidents, which came after many others in previous years, and recognise they were due to the family's disabilities.

Officers were called a total of 33 times in seven years but on many occasions never even visited the house.

Tew said that if the family's vulnerability been taken into account and the incidents linked, they would have been identified as hate crimes which "might have made a difference".

But at the time the force's hate crime policy did not even identify disability as a potential reason for being targeted.

Changes introduced following a review after the deaths meant that today the force "would have pulled all this together a lot earlier", Tew admitted.

He defended the lack of prosecutions, arguing that Pilkington had not wanted to take her complaints to court and many of the incidents did not amount to crimes but antisocial behaviour.

But the coroner, Olivia Davison, disputed his assertion, saying many of the attacks could have been prosecuted in the courts.

"It seems to me that, given the history and the context of the abuse, it would not have been antisocial behaviour but a crime because we had people being hounded in their own house," she said.

"It's Section 5 under the Public Disorder Act."

She added: "It seems we have seven or eight acts of parliament which are smack on to deal with the kind of behaviour this family faced."

Giving evidence, Tew read from an internal police review of the handling of the case that admitted too many of the reports of antisocial behaviour were closed without contact being made with the victims.

"The incidents of antisocial behaviour seem to have been treated in isolation without identifying the repeated victimisation and the disability of the family," he said.

The inquest, which is expected to end next week, continues.