A murder inquiry was launched today after a 52-year-old man died when a firework pushed through his letterbox sparked a blaze at his home.

Detectives are unsure whether the tragedy was the result of a prank that went wrong after the Little Brother rocket was shoved through the letterbox of Arthur Lonsdale's home in Witherwack, Sunderland.

Mr Lonsdale died in hospital on October 30 from respiratory failure caused by smoke inhalation, two days after the incident.

Northumbria Police said the death was being treated as a murder inquiry and appealed for help.

Detective Superintendent Steve Wade said: ''We know the firework started the fire at Mr Lonsdale's home but we do not know the intention of the people who did it.

''It could have been a prank which went wrong and there is nothing to suggest from our inquiries that he was being targeted.

''Mr Lonsdale lived alone but he was described by many people we have spoken to as popular.

''A lot of youths in the area used his home as a kind of drop-in centre and there are a lot of young people who are very upset about what has happened.

''I believe the answer to this murder is not very far from the crime scene itself and our inquiries are concentrating on this area.

''I have been a little disappointed by the response so far from the local community and would appeal to anyone with any information to come forward.

''I would also like to appeal for anyone living in the Witherwack area of Sunderland who sells this kind of rocket firework to come forward. ''Their information could prove crucial to this inquiry.

''We will treat anyone coming forward with information about supplying these fireworks sympathetically.

''We are dealing with a man's murder and need people to come forward.

''Mr Lonsdale's family, his mother Elsie, who is in her 80s, brothers Alan and Phillip, sisters June and Carol and son David have been left devastated by his death.

''People need to put themselves in the position of Mr Lonsdale's family and ask how they would feel if they had lost a much loved son, brother and father in such circumstances.''

Mr Lonsdale, known locally as Arky, was a former locksmith and a popular figure in the area.

He was a cat lover who provided a refuge for abandoned animals and a number of cats he was caring for died in the fire.