The funeral for David Bird, the twin brother and first victim of gunman Derrick Bird, is set to take place in Cumbria.
Mr Bird, 52, is believed to have been shot dead in bed at his home, High Trees Farm in Lamplugh, in the early hours of Wednesday June 2.
Bird later shot dead the family solicitor Kevin Commons, 60, before embarking on a murderous journey through towns and villages in West Cumbria, killing 10 more random victims before turning the gun on himself as police closed in.
The brothers' frail mother, Mary, 90, is not expected to attend the service at St Michael's Church, Lamplugh, due to her failing health. Among the mourners will be Mr Bird's estranged wife Susan, their three daughters Rachel, 28, Tracey, 26, and Katie, 19, and the twins' older brother Brian Bird.
Derrick Bird's elder son Graeme, 28, is also expected to attend his uncle's funeral though Bird's younger son, Jamie, 16, is not expected to attend. David was born five minutes before his brother and the twins have been described as "chalk and cheese", with the elder a cheerful, outgoing man in contrast to his brother.
Mr Bird's daughters have told family and friends they want the funeral to be a celebration of his life. While the family has denied reports of a feud between the two, one relative has said they were not particularly close. David owned a farmhouse in Lamplugh and had sold part of his land for a development of homes.
Derrick drove taxis and lived alone in a small two-up, two-down pebble-dashed terrace a few miles away in Rowrah. Their father Joe left £25,000 in his will to David but not to Derrick or their older brother. In a statement issued after his murder Mr Bird's daughters described him as a "loving husband and doting dad and granddad."
They denied suggestions of a family feud, adding: "Our dad's only downfall was to try and help his brother." Mr Bird's funeral will be led by the Rev Jim Marshall. There will also be a second funeral later for Mike Pike, 64, another of Bird's victims.
Mr Pike, who lived with his wife, Sheena, and son, Jason, 39, in Seascale, was shot dead while riding his bicycle through the town. He originally came from the Garston area of Liverpool where he worked as a shipbuilder before settling in Seascale, working at Sellafield for more than 30 years until his retirement in 2002.
The funeral for Mr Pike will take place at 2pm at Distington Crematorium, Workington. Derrick Bird's funeral will be held after all 12 of his victims have been laid to rest but further details have not been made public.