ST. JOHNS COUNTY, Fla. -

A man charged in connection with a 2007 unsolved homicide pleaded no contest Thursday to second-degree murder.

Phillip Pomper faces 35 years to life in prison when he's sentenced July 31 in the killing of 31-year-old Clark McWhorter.

On Jan. 28, 2007, McWhorter's body was found in the roadway on Coastal Highway in Guana State Park. An autopsy revealed he died from a single gunshot wound, deputies said. Investigators initially thought he had been run over by a car and killed.

After receiving tips from witnesses, detectives said they ascertained that Pomper, of Jacksonville, had specific knowledge of the killing.

With the assistance of the Jacksonville Sheriff's Office and the U.S. Marshals Service, detectives with the St. Johns County Sheriff's Office were able to locate Pomper.

During an interview, detectives said, Pomper admitted to his involvement in McWhorter's death. Pomper told investigators he did not know McWhorter (pictured right).

The information he provided led detectives to believe the killing was completely random and unprovoked, detectives said.

Investigators said McWhorter was walking alongside the road and it was raining that night. They said Pomper pulled up alongside him and asked if he needed a ride. Investigators said McWhorter got in the car, and that's when detectives said Pomper shot him.

"What he led detectives to believe is that the incident was not provoked," St. Johns County Sheriff's Office spokeswoman Cpl. Catherine Payne said. "He did not know the victim in the case."

The state attorney's office homicide investigative unit assisted detectives in obtaining a warrant for Pomper's arrest one year ago on a charge of first-degree murder.

Pomper was arrested in Jacksonville on two counts of sexual assault stemming from a different case. Investigators said he molested a young girl staying in his house.