A man is being questioned on suspicion of the murder of grandmother Marie Harding.
The 24-year-old was arrested by Metropolitan Police officers in a joint operation with Sussex Police yesterday afternoon.
He is being held at a north London police station while detectives quiz him over the death of Mrs Harding, 73.
She was found close to her daughter's home in Southwick with a single stab wound to her neck.
Chief Superintendent Mark Streater said: "We will continue to maintain a high visibility presence in Southwick and I hope this important development will provide a degree of reassurance to the public."
Thousands of fans held a minute's silence in tribute to Mrs Harding at the start of Brighton and Hove Albion's match against Queens Park Rangers on Saturday.
Seagulls players wore black armbands. Posters, printed by The Argus and appealing for information, were also put up at Withdean Stadium and close to where Mrs Harding's body was found on Wednesday.
Addressing the fans, Albion chief executive Martin Perry said "Marie loved working for the club and we loved to have her around.
"We have lost a friend and we want you to think of her at this time."
A tribute in the match programme read: "Marie was a turnstile operator for many years at the Goldstone ground and since 1997 worked part-time in the Queens Road ticket office.
"She had a great love for the club and worked extremely hard processing ticket applications. She was great fun and had a very positive outlook on life and was always smiling.
"Marie lived life to the full and was looking forward to a month's holiday in Australia with her husband Victor.
"The thoughts of all at the Albion are with Marie's husband Victor, daughter Julie and grandchildren Natalie and Daniel."
Mrs Harding, who had been walking along a secluded lane to her home when she was attacked, had dedicated her life to the Albion and her family are requesting that donations, instead of flowers, should be made to the club's £2 million appeal.
A note from the family on the club's web site said: "Can we please send our sincere thanks to everyone who has posted messages of condolence and support over the last couple of days. To know people are thinking about Marie is very comforting.
"Can we also thank people who have offered to send flowers and donations. We would, however, prefer rather than flowers, donations to be sent to Brighton and Hove Albion following their request for financial help, perhaps with a note to say that it is in memory of Marie Harding who so loved our club."
The Harding family are all avid supporters of the team and Mrs Harding's daughter Julie worked full-time in the ticket office.
Her granddaughter Natalie plays in one of the club's junior ladies teams, while grandson Daniel used to play for the Junior Seagulls.
Tim Carder, chairman of the Brighton and Hove Albion's Supporters Club, said: "We are a family club and the support is passed down from generation to generation. Mrs Harding was a lovely, caring lady who wouldn't have hurt a fly."
Anyone who wishes to make a donation in Mrs Harding's memory should send it to Brighton and Hove Albion, Tower Point, 44 North Road, Brighton, BN1 1YR.
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