Before the closing of my empty lot, I knew that there's

Before the closing of my empty lot, I knew that there's contamination of oil spill from a rusty container. The disaster happened in Jan, 2013, its about 900 litres of oil, but mainly on my neighbour's side. It took the engineering company, insurance company, and environment Canada over one year to settle the mess. I paid the deposit in Sept, 2013, but the P & S agreement stated clearly the lot that I purchased got to be nice and clean, and passed the Environment of Canada.
There's nothing wrong with the lot now, but that lousy builder put a fraudulent lien on my property, claiming that he has running around nearly 2 years and never got paid. He didn't continue his fraudulent lien, but removed by himself before expiry date.
The residents for that area knew that the old house on my lot should not be demolished, its just the last owner believed that lousy builder's word, he could sue the insurance company nearly 1.5 million. They worked together to cheat the insurance company. The lousy builder poured more oil near the house, and used his licensed enviro-remediation company to write reports and asked for air blowing fee every week.
My neighbour , who is a high school teacher, told me that if the court request her to testify the whole incident she'll go. This lousy just made her life miserable many times. She wants to see him going to jail.
My question is we know that this disaster ended up into criminal activities for both the builder and the last owner. The last owner wanted more compensation, and the lousy builder wanted the house demolished and sold to vic***** *****ke me , just purchased the empty lot and pay him to rebuild.
If the whole plot was to cheat the insurance company, can I report this to police and the insurance company, and let them start a full investigation. I don't need to start a new litigation against him? This lousy builder has made many victims' life miserable. My another neighbour across the street saw the whole incident from day one. He's willing to go to court and tell the public the whole incident.
The last owner , who is a house inspector for the Town, he was nervous about mentioning his old house. Both he and his wife even cried as people touching this topic.