Richard Nieuwenhuizen, 41, was assaulted after an under-17 match between Buitenboys Almere and Nieuw-Sloten Amsterdam on Dec. 2 and died the following day.
Last week, police arrested four teenagers, two of them aged 15 and two of 16. On Tuesday, they arrested three more teenagers and the 50-year-old father of a Nieuw-Sloten player, they said.
Some 12,000 people joined a silent march through Almere, a satellite town near Amsterdam, on Sunday in tribute to the volunteer linesman. (Editing by Clare Fallon)