An Ontario couple is suing the former owners of their home, along with a real estate firm and agent, after discovering the house they purchased had been the scene of a horrific double-murder -- a finding they say has led to anxiety, panic attacks and sleepless nights.

Eric and Sade-Lea Tekoniemi bought the home in Bowmanville, Ont., just east of Toronto, in the fall of 2011. They found out midway through the $253,000 purchase that Ron England, a paranoid schizophrenic, had murdered his 74-year-old mother and six-year-old stepdaughter in the home in 1996. Wanting to back out, they were told they were legally committed to follow through with the deal.

Now, a year later, they're suing the former homeowners, the selling agent and the real-estate firm that brokered the sale, claiming the discovery of the house's past has led to much anxiety and stress. The Takoniemis are reportedly seeking $450,000 in damages, plus legal costs associated with their lawsuit.

But an Ontario real estate lawyer says the couple may learn a tough lesson about buyer-beware: Ontario law only requires sellers and their agents to disclose information about known physical defects -- and not so-called “stigma” issues that may be attached to the property.

"In this case, we're not talking about a material physical defect ... there's a leak in the basement and it's going to cost $25,000 to fix and we can equate a dollar value to it,” Lawrence Dale told CTV’s Canada AM. "What we're talking about is a more subjective potential issue with the property -- which some people would call a stigma -- and the law isn't very developed in that area. It really is still an issue of buyer beware.”

The couple, their lawyers and the lawyers representing the former owners would not speak to CTV, because the case is before the courts. However, the Tekoniemis' lawyer, Marvin Hubberman, confirmed a civil action is underway against the three parties, saying he believes the defendants may have had an obligation to disclose knowledge of the murders.

Ontario real estate law doesn’t specify exactly what type of non-physical issues sellers are required to disclose, Dale said, noting it would be difficult for lawmakers to issue legal requirements around what are essentially subjective concerns.

While a gruesome history may have a negative effect on one person, another person may not be bothered by it at all, he added. "And more objectively speaking, it may not actually have an effect on the value of the property. And that's one of the things that, if it does go to trial, will be played out."

If prospective property buyers are worried about surprise discoveries related to the history of the property, they can ask their agent to add a clause into the purchase offer to require the vendor to acknowledge such issues as suicide, criminal activity and other “stigma” that may cause concern, Dale said.

"And then you know if the seller won't accept that clause, you've got a problem."

The issue has seemingly cropped up in other parts of Canada as well. Dale said the Real Estate Council of Alberta recently issued a directive to its members, saying they were not legally required to disclose "stigma" when selling a property.