Christian Charles Nielsen was born on May 2, 1975, in Rumford, Maine. When he was four years old, his parents divorced. Two years later, a judge ruled that his father would have custody of Christian and his younger sister. The judge decided this because Christian's mother was deemed not emotionally stable enough to care for young children.

As Christian grew up, those around him, including friends and classmates, described his behavior as normal. He did not stand out in any negative way during his youth. Between 2001 and 2004, he studied English at the University of Maine. However, he did not complete his degree.

On September 1, 2006, Christian Charles Nielsen invited James Whitehurst, who was staying at the Black Bear Inn, to go fishing. After having lunch at a Subway restaurant, they traveled to a wooded area in Upton. There, Nielsen shot Whitehurst multiple times in the head, killing him. Nielsen left Whitehurst's body in the woods and returned to his job. The next day, he decided to burn the body with gasoline instead of burying it.

On September 2, Nielsen murdered Julie Bullard, the owner of the inn. He suspected she would notice Whitehurst's absence. He broke into her bedroom while she slept and shot her three times in the head, chest, and back. After killing Bullard, he dragged her body into the woods, dismembered her with an axe and a hacksaw, and wrapped her in a tarp.

On September 4, Nielsen borrowed a chainsaw from his father. When he returned to the inn, Julie Bullard's daughter, Selby Bullard, and her friend, Cindy Beatson, arrived unexpectedly for Labor Day. Concerned they might ask about Julie, he shot both of them in the head. Following their deaths, he used the chainsaw and hacksaw to dismember their bodies, cutting off their fingers and removing their rings to hide evidence.

Later that day, Nielsen called his father, saying he was running the inn while Julie was in California. When his father and stepmother arrived, they found one of the bodies outside and called the police. Before law enforcement arrived, Nielsen's stepmother reported that he had confessed to her about the murders. He was arrested without resistance and provided a detailed confession about the killings, including the location of Whitehurst's body.

Initially, Nielsen pleaded not guilty but later changed his plea to guilty. He had attacked another inmate while in jail and was transferred to a different facility. During his time in custody, he lost a significant amount of weight during a hunger strike. After being evaluated, his lawyer changed his plea to "not criminally responsible" due to mental health issues. Despite this, he was deemed competent to stand trial. On October 18, 2007, he was sentenced to four concurrent life terms and is currently held at Maine State Prison.