Toronto authorities are still stumped over a hole found near a Pan Am Games tennis venue. It was discovered on January 14 by CBC news.

Toronto Police Deputy Chief Mark Saunders told reporters the hole measured 6 feet high, 33 feet long, and almost 3 feet wide. Authorities discovered a rosary and a Remembrance Day poppy, which is used to honor “Canadian veterans who died in combat.” Saunders also said more than one person probably dug the hole, but nothing suggests the people used it for criminal activity or terrorism.

“There is nothing right now that suggest that this is criminal,” he told the media. “We’re trying to find and establish right now who built it, why they built it and what were their intentions. There is no criminal offense for digging a hole.”

They also found a generator, sump pump, gas can, food, drinks, work gloves, wheel barrow, and light bulbs. Ice on the sump pump indicated that those who constructed the tunnel used it this winter.

“This was built with a considerable amount of sophistication,” Saunders explained. “The individuals responsible for building it clearly had some expertise in structural integrity.”

Authorities did notify national security officers even though they do not believe the people involved are criminals. CBC spoke to Ray Boisvert, a former assistant director of intelligence at the Canadian Security Intelligence Service and now CEO of the risk mitigation firm ISECIS. He does believe the people involved wanted to use the tunnel for criminal activity:

“Nobody would build something like that without a specific purpose,” Boisvert told CBC Radio’s Metro Morning.

That purpose could be to launch an attack against York University or the Pan Am Games, he said, especially because the tunnel doesn’t seem to be the work of a survivalist or drug producer.

Boisvert said police likely mounted a surveillance operation at the site, but it’s possible whoever dug the hole abandoned it and went into hiding once they saw police respond to the initial discovery of it some five weeks ago.

“What worries me now is we may never know who was behind that thing,” Boisvert said.

While Boisvert said the decision to call in national security officers was to guard against the “worst-case scenario,” the move makes sense given the attention that will be on this summer’s Pan Am Games.

“The Games are definitely in the target zone,” he said.

Toronto filled the tunnel and placed a wood lid over the top.