Nelson Hart was born in 1968 in Newfoundland and Labrador, Canada. He suffered from epilepsy and had a limited education, reportedly only completing up to Grade 5. Hart and his wife, Jennifer Hicks, faced financial difficulties and relied on social assistance. They had twin daughters, Karen and Krista, born in 1999. The family experienced instability, including periods of homelessness, and were under the supervision of social services due to concerns about their living conditions and Hart's health issues.

On August 4, 2002, Nelson Hart took his three-year-old twin daughters, Karen and Krista, to Little Harbour on Gander Lake, Newfoundland. Later that day, both girls drowned. Hart claimed that one daughter fell into the lake and, due to his inability to swim and a potential epileptic seizure, he was unable to save her. He then drove home to get his wife instead of calling emergency services. By the time help arrived, both girls had drowned.

In 2005, the Royal Canadian Mounted Police (RCMP) conducted a "Mr. Big" sting operation, wherein undercover officers posed as members of a criminal organization to elicit a confession from Hart. During this operation, Hart confessed to deliberately pushing his daughters into the lake and reenacted the incident. This confession led to his arrest and subsequent conviction for first-degree murder in 2007.

However, in 2012, the Newfoundland and Labrador Court of Appeal overturned Hart's conviction, citing concerns about the admissibility and reliability of the confession obtained through the Mr. Big operation. The Supreme Court of Canada upheld this decision in 2014, ruling that such confessions are presumptively inadmissible due to the potential for coercion and unreliability. As a result, the Crown dropped all charges against Hart, and he was released from custody after serving nine years in prison.