Chatham County man re-indicted in 2023 Truman Parkway killings of son’s girlfriend & good samaritan

by Madalyn Bierster

SAVANNAH, Ga. (WTOC) - A Chatham County man accused of killing his son’s girlfriend and a Good Samaritan along the Truman Parkway in 2023 was re-indicted yesterday, weeks before his murder trial is scheduled to begin.

Derek Johnson, 49, faces charges in the deaths of 19-year-old Shaliyah Collins and 48-year-old Phillip Mock. Both were found shot to death on the Truman Parkway in October 2023.

The new indictment includes two counts of malice murder, two counts of felony murder, two counts of aggravated assault, aggravated assault family violence for pointing a gun at his wife, concealing the death of another, and five counts of possession of a firearm during the commission of a felony.

The incident

According to investigators and Collins’ family, Collins was picked up from work that night by her boyfriend’s mother and Johnson, her boyfriend’s stepfather. Her family says she became afraid during the drive and believed her life was in danger. They say she opened the car door and jumped out along Truman Parkway, trying to escape.

Police say Johnson then chased after Collins on the side of the road and shot her three times, including once in the head.

The second victim, Phillip Mock, 48, was driving by and saw what was happening. Investigators say he pulled over and got out of his vehicle to try to help the teenager. Police say Johnson then turned the gun on Mock and shot him as well, killing him.

Records indicate Mock was on the line with 911 for more than 50 seconds during the attack, but no one answered, Savannah Police confirm.

When officers arrived on scene, they found Mock shot to death near the roadway. Collins’ body was discovered in a marsh below the Truman Parkway.

The indictment alleges Johnson threw Collins’ body into the marsh to hide evidence.

Arrest and investigation

Johnson, the stepfather of Collins’ boyfriend, was identified as the suspect. He was arrested nearly two days after the shooting in St. Petersburg, Florida, more than 300 miles away.

Investigators have not revealed a motive in the case.

About the victims

Mock was a loving father, husband and grandfather, according to his family. He worked as an auto technician for over 30 years at Saturn of Savannah and Dan Vaden Chevrolet and Cadillac. He was on his way to pick his daughter up from work when he stopped to help Collins.

Tyler Heath, Mock’s relative, remembered him as a caring person. “That’s what he was, just a good Samaritan. He would help people even when they didn’t ask for it and that’s exactly what he was doing,” Heath said.