William Michael Parente was born on July 20, 1949, in Bay Ridge, Brooklyn. He was the only child of Willie and Roccolyn Parente. His father was a New York State Police trooper. William spent his childhood in Bay Ridge and enjoyed summers with his family in Long Beach.

William graduated from Brooklyn College and then Brooklyn Law School. His uncle, Anthony J. Russo, helped pay for his tuition at both schools. After completing his education, he became a lawyer and began working in a Manhattan office on the Avenue of the Americas. His colleagues viewed him as a hardworking family man. He was polite to his secretary and worked long hours, but not excessively long. He did not curse and did not usually socialize over drinks after work.

In 1977, William married Betty Mazzarella. After becoming a member of the New York bar, he joined a law partnership on Wall Street. In 1988, he moved into private practice, as his wife was expecting their first child. The family moved to Garden City, New York, but William often returned to his old neighborhood in Brooklyn. They kept in touch with friends and visited his mother. William also enjoyed bringing his two daughters back to Brooklyn for Halloween, where they would go trick-or-treating.

Later in his career, William was involved in making loans that he referred to as "bridge loans." These loans were often high-risk and were made to projects waiting for permit approval. To fund these loans, he reportedly used assets from investments he managed. However, problems arose when he could not return funds to at least one investor who asked for their money back.

On April 20, 2009, the bodies of four people were found in room 1029 of the Sheraton hotel in Towson, Maryland. The victims were identified as William M. Parente, his wife Betty Mazzarella Parente, and their two daughters, Stephanie and Catherine. The police were called when hotel staff discovered the bodies. The cause of death for all four was asphyxiation.

Authorities believe that the murders happened at different times. Betty was thought to have been the first victim on April 19, during the day. Catherine was likely killed soon after. Both were found on a bed in the hotel room. Stephanie, who was visiting her family from Loyola College, was believed to have been killed later that same Sunday. Around midnight, her roommate called the hotel room to check on her. William answered and told the roommate that Stephanie was there. The roommate later noted that William sounded "odd" on the phone.

The investigation suggests that William Parente took his own life sometime on Monday morning. Hotel staff noticed that the family did not check out as expected, raising concerns from Loyola College about Stephanie's absence that day.

Investigators later learned about William Parente's financial troubles. At the time of the murders, he was under investigation by the FBI for a possible Ponzi scheme. This scheme may have involved defrauding investors of around $20 million. Complaints against him had been filed, with some investors reporting significant financial losses.

The case was notable as one of two familicides in Maryland that week, bringing attention to the topic of domestic violence and economic distress. William Parente's funeral service was held separately from those of his wife and daughters.