Philip Markoff was born on February 12, 1986, in Sherrill, New York. He was the son of Susan Haynes and Richard Markoff, who worked as a dentist. Philip had an older brother named Jonathan and a half-sister from his mother's second marriage. As a child, he grew up in a family that valued education and community involvement.

In 2004, Markoff graduated from Vernon-Verona-Sherrill High School. During high school, he was an active student and a member of several clubs. He was part of the National Honor Society, the History Club, and the Youth Court. He participated in sports as well, including bowling and golf.

After high school, Markoff attended SUNY Albany, where he studied pre-medicine. He graduated in 2007 and continued his education by applying to medical schools after taking the MCAT. At the time of his arrest in 2009, he was a second-year medical student at Boston University School of Medicine. However, he faced suspension from the school after criminal charges were brought against him.

In 2005, Markoff met Megan McAllister, who was from New Jersey. They both volunteered at Albany Medical Center in the emergency room. The couple became engaged, and their wedding was planned for August 14, 2009. Megan was set to begin medical school in the fall of that same year.

Philip Markoff was suspected of being involved in three robberies that occurred in 2009. The first incident happened on April 10 at the Westin Copley Place Hotel in Boston. Trisha Leffler, an escort, was bound, gagged, and robbed at gunpoint during this robbery. Just days later, on April 14, Julissa Brisman, who had posted a massage service advertisement online, was found dead in her hotel room at the Copley Marriott, also in Boston.

The third crime took place on April 16 at a Holiday Inn Express in Warwick, Rhode Island. Cynthia Melton, an exotic dancer who offered lap dance services, survived an attempted robbery there. Police believed these three incidents were connected because they happened close together in time and shared similar characteristics.

Investigators used security camera footage, cell phone records, and email evidence to link Markoff to the robbery of Trisha Leffler and the murder of Julissa Brisman. On April 20, 2009, authorities arrested him in Walpole, Massachusetts. He was in a car with his fiancée on their way to Foxwoods Casino in Connecticut.

Markoff was arraigned on April 21 in connection with Brisman's death. The prosecutor stated that police found a semi-automatic handgun, wrist restraints, and duct tape in his apartment. Markoff pleaded not guilty to all charges. On May 4, 2009, Rhode Island officials issued a warrant for Markoff for the attempted robbery of Cynthia Melton, but they decided to wait until the Boston charges were resolved before proceeding.

His trial was initially set to begin in July 2010. However, it was delayed until March 2011.

While he was in custody, Markoff made several suicide attempts. His fiancée eventually visited him in jail and canceled their wedding. She expressed her belief in his innocence at first but later indicated she would not visit him again.

On August 15, 2010, Markoff was found dead in his cell. He had used a makeshift knife to inflict injuries on himself, along with some unusual methods of asphyxiation. Before his death, he wrote his fiancée's name and their pet names in blood on the wall of his cell and left photographs of the two of them scattered around.