Melissa Lawless was born on February 23, 1981, in Orange County, California. She grew up in a family with her mother and father. Little is known about her early childhood and home life. Melissa later had a daughter, and she was known to be involved in her child's education.

As an adult, she lived in Tracy, California, where she worked as a Sunday school teacher. Melissa had connections in her community, including friendships with families living in her mobile home park. She had some struggles with her mental health, which included diagnoses of borderline personality disorder, bipolar disorder, and schizophrenia. Despite her troubled state, she continued to work and interact with children in her Sunday school class. 

On March 27, 2009, Sandra Cantu, an eight-year-old girl, went missing in Tracy, California. She was last seen after leaving her home to play at a friend's house. When she did not return for dinner, her family reported her missing. Local police and the FBI began searching for her, using dogs, helicopters, and volunteers from the community.

A few days later, on April 6, a suitcase was discovered in an irrigation pond. Inside, investigators found Sandra's body. An autopsy revealed that she had been abused and smothered. The search for her killer intensified.

Melissa Huckaby, a 28-year-old local Sunday school teacher, became a person of interest. On the day Sandra disappeared, Huckaby sent a text message to the girl's mother, claiming something had been stolen around the same time. The next day, during a vigil for Sandra, Huckaby acted very agitated and claimed to have found a note informing where Sandra's body was hidden.

The police noticed that Huckaby's behavior was odd. She had a history of mental health issues and appeared to be seeking attention. As the investigation continued, witnesses reported seeing Huckaby's SUV near the pond around the time Sandra went missing.

Huckaby had reported a suitcase stolen around the same time Sandra disappeared. A rolling pin found at the church where she worked tested positive for Sandra's DNA, indicating a possible connection.

On April 10, 2009, Huckaby was arrested and charged with murder, kidnapping, and other charges. She later pleaded guilty to first-degree murder and kidnapping as part of a deal to avoid the death penalty. Huckaby was sentenced to life imprisonment without the possibility of parole. At her sentencing, she expressed confusion about her actions, stating she would struggle to understand her motives for the rest of her life.