"This would be brand new territory for us in terms of something of this magnitude," said Howard Normann, acting manager of the board's urban forestry division.
"I can assure you that the park board and the city would push hard for the maximum penalty, whatever that would be," he said Thursday.
The seven-year-old trees that lined both sides of the street in the city's west side were discovered felled by residents in the early hours of Jan. 7. Each 4.5-metre maple had been sliced at about waist height, its branches toppling onto the lawn.
Normann said a rechargeable, cordless saw with a fine blade may have been used.
"They put it at a bit of an angle and they just went boom, boom," he said. "Then they crossed the street and every one of those trees was fallen in a westbound direction."
The board started its investigation after residents awoke to branches splayed along their street.
One woman reported that she arrived home from work at 12:30 a.m. with the trees intact, but her husband made the discovery as he left for work at 6:30 a.m. that day.
The board reviewed its records to determine if anyone might have been disgruntled by the trees obstructing their view but turned up nothing.
The case was turned over to police, who are looking into video from security cameras mounted on some homes in the area.
The trees were planted in November 2010 at a cost of $10,000. The board will spend that much more as it plans to begin replanting on Monday.
Normann said a fine is one potential consequence for the bylaw violation, but noted the Crown would have to make that determination if a suspect is tracked down.
"It's a violation of more than just a written bylaw," he said. "These people care. The trees on their streets are a place for their kids to climb, they offer shade, they filter pollution.
"Trees are an important part of every neighbourhood of this city. I started talking to people and they sure were upset."