Duffy was born on May 10, 1976, in the small town of Norcross, Georgia.

On June 24, 1997, 40-year-old Priscilla Culberson was reported missing after she didn't show up for work. The police started investigating and found her purse and some bloody items by the side of a road in Atlanta. Her body wasn't discovered until the next day when her 20-year-old daughter found her naked body in an empty lot near a bus terminal. Detectives collected semen samples from the killer and blood from Culberson, which showed she had fought back. These samples were taken as evidence.

On July 30, at around 5:00 pm, 42-year-old Gwendolyn Wyche was shot multiple times in the back outside her home. She was the daughter of Minister O.L. Blackshear. The police found her lying on the sidewalk and rushed her to Dekalb Medical Center, but she couldn't be saved and was pronounced dead soon after. Initially, the police thought the motive for the killing was a failed robbery. The suspect was seen driving a blue vehicle, and the weapon used was a revolver.

Just two days later, on August 1, 52-year-old Pok Yeo Kim was working when a robbery happened. The assailant shot her and stole money from the register. A surveillance camera captured the robbery, and the suspect was described as a black man, 5'10" tall, about 160 pounds, and around 23 years old.

The police eventually connected the last two murders and released the surveillance video to the public, hoping for leads. A woman contacted the investigators and identified her son, 21-year-old Charles Lee Duffy, as the man in the video. Duffy, who had been convicted of robbery and auto theft, was on probation at the time of the murders. The detectives focused on Duffy and confirmed his involvement in Yeo Kim's death with a partial fingerprint match. They went public with this information, but Duffy didn't turn himself in, despite his mother's pleas.

A few days later, the police picked up a man walking alone who seemed to be high on drugs. He claimed to be Tarus Smith and had a screwdriver, so he was arrested and sent to the Chamblee City jail. Later, they discovered that this man was actually Duffy, which relieved the investigators since they believed he was a danger to society.

Duffy confessed to the killings of Yeo Kim and Wyche, avoiding a trial. In March 1998, he pleaded guilty to both murders and was sentenced to life in prison without parole.

In 2003, Fulton County District Attorney Paul Howard formed the Fulton County Cold Case unit to re-examine unsolved cases. In 2005, they re-investigated Priscilla Culberson's murder. The semen found on her body was tested and matched Duffy's DNA, which was on record from his imprisonment. Confronted with this evidence, Duffy confessed and in 2007, received another life sentence without the possibility of parole.