Why has Artur been killed?

The Woods miniseries starts with finding a body of a man - Artur - who has been presumed dead for the last 25 years, where 4 teenagers went missing in the woods and only two bodies have been found. His death restarts the whole investigation, in which Pawel, the main character who lost his sister that day, discovers the truth.

We know that Artur just before his death also was digging in that case - but why was he murdered?

We know that his killer was Dawid Goldsztajn, the camp owner, who lost lots of money thanks to the civil suits following the incident, but why did he kill Artur? He could easily drag him out from hiding, expose him and his parents, clear own's name and maybe even recover the money. Instead, he just shot the only person who could prove the existence of the conspiracy.

Was that pure revenge?