Jeffrey Robert MacDonald was born on October 12, 1943, in Jamaica, Queens, New York. He was the second of three children born to Robert and Dorothy MacDonald. Jeffrey grew up in a poor household on Long Island. His father was a strict disciplinarian who demanded obedience and achievement but was not violent towards his family.

Jeffrey attended Patchogue-Medford High School, where he was active in student government. He became the president of the student council and was voted "most popular" and "most likely to succeed." He also made an impression as the king of the senior prom.

During his eighth-grade year, Jeffrey met Colette Kathryn Stevenson. He first noticed her walking down the hallway with her best friend. He found Colette very attractive, and after a couple of weeks, they began talking and formed a friendship. They started dating and had a brief romantic relationship in the ninth grade. Jeffrey later recalled falling in love with Colette while watching a movie together. However, their relationship ended the following summer.

After their breakup, Jeffrey dated another girl named Penny Wells. His time in high school was marked by academic success, which led to a three-year scholarship at Princeton University, where he enrolled as a premedical student in 1962.

In college, Jeffrey worked hard on his studies, and after his second year, he reconnected with Colette, who was then attending Skidmore College. They exchanged letters regularly, and Jeffrey frequented visits to her college. In August 1963, when he learned that Colette was pregnant, he decided to marry her. They got married on September 14, 1963, with nearly one hundred guests attending the ceremony.

Jeffrey and Colette welcomed their first daughter, Kimberley Kathryn, on April 18, 1964. After finishing his undergraduate studies at Princeton, Jeffrey briefly worked as a construction supervisor before moving to Chicago to attend Northwestern University Medical School in 1965. Colette stayed home to care for their daughter while Jeffrey focused on his studies, often working part-time jobs to help support the family. Their second daughter, Kristen Jean, was born on May 8, 1967.

After graduating from medical school in 1968, the family moved to Bergenfield, New Jersey, while Jeffrey completed a year-long internship in thoracic surgery. He described the internship as very demanding, often working 36-hour shifts. At the end of his internship, he and Colette vacationed in Aruba before Jeffrey joined the U.S. Army.

He was commissioned in the Army on June 28, 1969, and sent to Fort Sam Houston, Texas, for training. He volunteered for the Army's Special Forces and completed paratrooper training in Fort Moore, Georgia. Later in 1969, he was assigned to Fort Bragg, North Carolina, as the surgeon for the 3rd Special Forces Group. The family settled into a home on the base, where Colette aspired to become a part-time teacher, and their daughters grew up with distinct personalities.

In December 1969, Colette was pregnant with their third child. Shortly after Christmas, Jeffrey surprised his daughters by buying them a Shetland pony. By 1970, Jeffrey held the rank of captain and planned to study advanced medical training at Yale after his military service.

At 3:42 a.m. on February 17, 1970, emergency dispatchers at Fort Bragg received a frantic call from Jeffrey MacDonald. He reported a stabbing at his home and shouted for help. Moments later, the line went quiet.

Within ten minutes, military police arrived at his address, 544 Castle Drive. They found the front door locked and darkness inside. When no one answered, they checked the back, where they discovered the back door wide open. Entering, they found Colette MacDonald dead on the bedroom floor. She had multiple injuries, including stab wounds and blunt force trauma. Beside her, Jeffrey was found alive but injured. He was lying on the floor with his head on Colette's chest and called out for his daughters.

Five-year-old Kimberley was found in her bed, also brutally injured. She had been struck and stabbed multiple times. In the next room, two-year-old Kristen lay in her crib, having suffered even more severe injuries, including numerous stab wounds.

Nearby, the word "PIG" was scrawled in blood on the headboard of the marital bed. After being treated for his own less severe injuries, Jeffrey was transported to a nearby hospital, continually asking about his children.

In the days following the murders, investigators recovered murder weapons—a knife, an ice pick, and a piece of lumber—just outside the back door. These items were linked to the MacDonald home and had been wiped clean of fingerprints.

The investigation soon focused on MacDonald's account of the events. He claimed four intruders—three men and one woman—attacked him and his family. His descriptions of the intruders included a woman with a candle chanting about acid. However, investigators found little evidence to support his version of events. The crime scene showed minimal signs of struggle, and neighbors reported hearing only Colette's voice.

Authorities conducted forensic analysis, which indicated inconsistencies in MacDonald's narrative. Blood evidence suggested that the family had been attacked in separate locations inside the house, contradicting his claims that all had been assaulted at once. MacDonald's blood was found in limited areas, while evidence from the victims was scattered throughout the home.

As the investigation continued, suspicions grew regarding MacDonald's guilt. He was charged with three counts of murder in May 1970. The case underwent various legal actions and hearings over the years, eventually leading to his trial in 1979. During that trial, he maintained his innocence, but the jury found him guilty of murdering his wife and daughters.

MacDonald was sentenced to three consecutive life terms and was later incarcerated. He has consistently claimed his innocence throughout the years, despite multiple appeals and extensive media attention surrounding the case. The death of his family remains one of the most litigated murder cases in American history, and the question of his guilt persists in public discourse.