"We're trying to find and establish who built it, why they built it and what were their intentions," Deputy Chief Mark Saunders said, of the find in the heavily wooded Black Creek parkland 82 feet from the fenceline of tennis courts at the Rexall Centre.
"There is nothing to suggest criminality," said Saunders, noting that digging the tunnel may break provincial statutes or bylaws but there is no criminal intent. "I don't have a working theory. We're open. We go with the evidence."
Police responded and found the chamber, which lay 10 feet underground and spanned 33 feet, was over 6 feet high and nearly three-feet wide supported by lumber. There is no evidence of machinery used in the excavation of the tunnel.
"This was built with a considerable amount of sophistication," said Saunders, of the structure built with 2 x 8 wood framing and plywood walls. "The individuals responsible for building it clearly had some expertise in structural integrity."
Saunders said the Toronto Police Service has consulted with provincial, national and international partners during the investigation and have discovered no links at this time to a terrorist threat.
He also noted the entrance was concealed by dirt over a wood lid.
Investigators want to hear from anyone who may have seen something suspicious in the area or someone moving building materials in the area.
Police collected all the forensic evidence from the tunnel that has now been filled in.
Police found a gas can, food and beverage containers, work gloves, a wheel barrow, as well as moisture-resistant light bulbs, a gas generator and a sump pump to remove ground water.
There were also rosary beads with a crucifix and a poppy affixed to it and hanging from a nail inside
Anyone with information is asked to contact police at 416-808-3100, Crime Stoppers anonymously at 416-222-TIPS (8477), online at 222tips.com, text TOR and your message to CRIMES (274637), or Leave A Tip on Facebook. Download the free Crime Stoppers Mobile App on iTunes, Google Play or Blackberry App World