Ex-wife testifies she watched Derek Johnson shoot two people on Truman Parkway

SAVANNAH, Ga. (WTOC) - The ex-wife of Derek Johnson took the stand Monday on day three of his double murder trial, testifying in detail about the night Johnson allegedly shot and killed two people along the Truman Parkway in 2023, including forcing her to help throw one victim’s body off an overpass.

Johnson is accused of killing 19-year-old Shaliyah Collins, their son’s girlfriend, and Phillip Mock, a bystander. Testimony says Johnson shot both victims in a fit of rage.

Surveillance video shown, events before the shooting described

Prosecutors played surveillance footage from a Walmart at Montgomery Crossroads, around 11:00 p.m., showing Collins getting into the back driver’s side of the vehicle and Johnson in the driver’s seat.

Lakia Johnson confirmed Johnson had been making comments toward Collins’ co-workers before she got into the car.

The two were married at the time, before divorcing in September of 2024.

She testified that after the vehicle left the Walmart, it traveled northbound on the Truman Parkway toward Victory Drive. During the drive, she said Collins had earbuds in and was listening to music, unaware of what was unfolding.

Lakia Johnson said her ex was calm at first, but became agitated after passing the Victory Drive exit and began accelerating. She said she repeatedly tapped his leg and asked him to slow down.

“I just remember him saying, no, no, and he was just gripping the wheel,” she said.

Johnson pulls over, orders women out of car

Lakia Johnson testified that Johnson eventually pulled over in the shoulder lane near a graveyard on the Truman Parkway. She said he put the vehicle in park and ordered both women out.

She said she got out immediately and stood by the passenger door. She said Collins, still confused, was asking “What’s going on?” when Johnson pulled a gun from the center console, opened Collins’ door, and pulled her from the vehicle by her arm.

“He said, b----, get the f--- out of my car,” Lakia Johnson testified.

She said Collins was pulled into the middle of the highway and tried to back away while Johnson advanced on her. Lakia Johnson said she screamed at Johnson to leave Collins alone as cars passed by.

“I heard the first pop,” she said. “And then I heard the second pop. And as she fell to the ground, I was like, oh my God. And then he stood over her and shot her in the head.”

Body thrown from overpass

Lakia Johnson testified that after shooting Collins, Johnson picked up Collins’ body with his left hand, carried it to the overpass railing and held it over the edge. He then ordered her to come help.

“I was just scared if I didn’t do it,” she said. “He said he was going to shoot me.”

She said she held Collins’ feet, and Collins went over the railing.

“She went over,” Lakia Johnson said. “And I was just standing there like I was shaking and everything. Just standing there. And he was like, get your a-- back in the car. Just demanding me angrily.”

Second victim shot after approaching car

After Johnson ordered Lakia Johnson back into the front passenger seat, she testified she saw Phillip Mock’s vehicle parked on the shoulder ahead of them, with its emergency lights on. She said Mock was walking toward the car.

Johnson pulled out his gun and told her to put her seat back, she said. The passenger window was down.

“He came to the car and asked, was everything OK?” she testified. “Johnson already had his gun out and he fired one shot and then he fired the second shot and that’s when I heard Mr. Mock holler out.”

She said she did not see what happened to Mock after the shots were fired.

Alleged cover-up after the shootings

Lakia Johnson testified that Johnson drove from the Truman Parkway to the back of his apartment, where he sat in the car and repeatedly said, “Where did that white man come from?”

She said Johnson then forced her to cut up the victims’ cards and ID, made her change out of the clothes she wore that night, and allegedly sprayed them down with hydrogen peroxide.

Overnight, she says she and her husband stayed in the car outside there home at Chelsea Apartments til 7 a.m.

She also testified that Johnson took her phone and keys that night and didnt give them back til the following afternoon.

“Dont say anything... you wasn’t in the car. Shaliyah was trying to kill me.” is what she testified that her husband told her in the hours that followed.

She also says her then-husband told her if she said anything, she would be crying for one of her own.

At this point, she testifies all of Shaliyah’s stuff was still in the back seat.

She says the following day after belongings were cut up, they were disposed of at various places across the Woodville/Garden City/ Liberty City/Pooler areas, and that her ex was throwing stuff out of the window as he drove, on both sides of the road.

The next day, she says her son called her once she had her phone back, that detectives were at their home on Holly Avenue.

Once she arrived, detectives told Johnson and her son (the victim’s boyfriend) of Shaliyah’s passing.

She broke down in tears with her son. A point the defense called out, asking why she was fake crying if she already knew Collins was dead.

She responded, saying she was still upset at what she had witnessed.

She also said she has not seen her ex since the two went their separate ways that day.

She later went to the police station and told the police everything that happened, her 2nd time speaking with them.

Relationship with victim

During her testimony, Johnson said she had a good relationship with Shaliya. She had bought the teen clothes when she got her first job at Walmart so she could have something to wear.

She and her 3 sons often spent time with Collins.

The trial is set to resume with additional witnesses Tuesday.