The cedar checkpoint shelter built this spring at the Six Mile Bridge near Juskatla was burned to the ground the night of June 30.
Masset RCMP are investigating the incident but say they have no witnesses and no suspects at this time.
The fire was reported just after noon on Friday, he said. On Monday (July 4), another structure at the site was pulled down.
The buildings have no reported value, said Corporal Bob Isaacs, and there aren't many leads in the case.
"If we have something to work with, we work with it," he said. "Someone may say something to someone down the road and then we will find out."
The buildings had a symbolic value for many islanders, said Haida Nation vice-president Arnie Bellis. They were erected during the protest action which stopped logging in TFL 39 for several weeks in March and April.
"Of course we don't know who did it but sooner or later we're going to find out," Mr. Bellis said. "It might have been a wooden structure, but it was a symbol of a unified front."
Mr. Bellis said the person or people involved in the vandalism should come forward and make a public apology to all islanders.