Three teenagers have been arrested in connection with the death of a mother who died after a firework was pushed through her letterbox, setting her house ablaze.
Mary Fox, 59, who had nine children, was trapped in her bedroom after reportedly pushing her son Raum, 17, to safety through an upstairs window as flames engulfed the house.
The youths, two aged 17 and one of 18, are all from Bodmin in Cornwall.
The remnants of a firework were found behind the front door of Mrs Fox's house in Carpenter Court, Wallace Road, Bodmin.
The three were arrested on suspicion of murder and are in custody at Launceston police station.
After leaping from the three-storey house, Raum ran to alert neighbours that his mother was still trapped inside. Firefighters found Mrs Fox dead in the same room from which her son escaped.
Officers have investigated claims that Raum, who has learning difficulties, was being bullied at school and that the family was targeted by youths who had been throwing fireworks in the street.
It is thought Raum moved from Bodmin College to St Austell College because of bullying.
But Devon and Cornwall police said there is no obvious evidence that Mrs Fox or Raum had been victims of bullying after speaking to schools and social services.
They were held in custody after detectives said they found clues on Facebook to what is being treated as murder. Officers acted on reports suggesting people had posted the suspects' names on the internet.