(CNN) -- Four more arrests have been made in connection over the death of a Dutch volunteer soccer official who was allegedly beaten by teenage players at an amateur game earlier this month.
Dutch police said Tuesday they had arrested two 16-year-olds, a 17-year-old and a 50-year-old man.
The latter is the father of a player of the Amsterdam junior side Nieuw Sloten that played in the match against SC Buitenboys, for whom 41-year-old Richard Nieuwenhuizen had volunteered to act as linesman for the December 2 game.
There are now a total of eight people in custody following the arrest of four teenagers last week, and Dutch police have asked for anyone with photos or video recordings of the attack to come forward.
If convicted of charges of manslaughter and assault, the two 15-year-olds in detention would serve a maximum sentence of one year in a youth prison -- while the 16-year-olds could be jailed for up to two years, unless judges rule that they should be treated as adults.
Nieuwenhuizen's son was playing for Buitenboys when the incident occurred in the city of Almere. The linesman reportedly fell into a coma after he was beaten, and he died the next day.
Last weekend, 33,000 amateur football games across the Netherlands were canceled in tribute to Nieuwenhuizen, who was buried on Monday.
Nieuwenhuizen's death has resonated across the globe, with FIFA president Sepp Blatter among those extending condolences.
"Football is a mirror of society, and sadly the same ills that afflict society -- in this case violence -- also manifest themselves in our game," the head of world soccer said in a statement on FIFA's website.
"Nevertheless, I remain convinced that football -- through the example set by the tireless efforts of people like Mr. Nieuwenhuizen -- is a force for good, and we must continue to use its positive example to educate people against these wrongs."
Despite a relatively small population of 17.5 million, Holland has built an outstanding reputation for developing young footballers over the years, with its amateur youth clubs providing a strong breeding ground for the country's professional clubs.