John Johnson, his wife, Kathy, and their daughter, Christy, said the realtor did not tell them of the February 2006 incident when Eustis police Officer Michael Mount shot and killed his wife Kim, fellow Officer Jose Gomez and Gomez's wife, Serena, WKMG-TV, Orlando, reported Monday.
John Johnson said he learned of the murders from neighbors.
"He said, 'Oh no, there was a triple-murder suicide here,'" John Johnson said. "I was like, 'You are kidding me, right?'"
A 2003 law protects realtors from having to disclose unpleasant facts about a house's past. Kathy Johnson said the law should be changed.
"(We) just (want) somewhere for people to go and get some answers," Kathy Johnson said.
The realtor has agreed to waive commission fees to help the Johnson family resell the home.
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