ROCKBRIDGE COUNTY, Va. (WFXR) — The trial for a Roanoke man facing manslaughter charges in connection with a 2019 explosion took a turn on Tuesday as prosecutors said they proved the man overfilled the fuel tanks at the Rockbridge County station, reportedly causing the fire, while the defense’s first expert witness claimed the incident happened because of missing safety equipment on and in the tanks.

The explosion at the South River Market on May 10, 2019 killed four people, including the owner of the store, Roger Lee Roberts; two employees, Kevin Tate Roberts and Samantha Gail Lewis; and a patron, Paul Dewayne Ruley.

Phillip Ray Westmoreland, the driver of the truck that delivered the fuel to the gas station, was arrested on March 19, 2021 and charged with four counts of involuntary manslaughter, according to Rockbridge County court records.

More than 17 months after Westmoreland’s arrest, a mechanical engineer with S-E-A, Ltd. — Christopher Cassino — took the stand on Tuesday, Aug. 23

Cassino specializes in pipes and systems that lead to fire or explosions, but he is also trained for going into dangerous chemical situations. His goal in the investigation was to figure out what could have attributed to the deadly incident at the South River Market.

Cassino and the team investigating the scene ran several tests on the fuel tanks and the pipes leading to the tanks to see if there was any leaking or damage that could have caused the explosion.

The purpose of this was to measure the integrity of the tank and pipes during the time Westmoreland delivered gasoline.

Christopher Cassino testifies in Rockbridge County on Aug. 23, 2022. (Photo: WFXR News/Pool camera)

The results of the test showed that the pipes and the tank were tight, so gasoline never could have leaked out from them.

“There were no other penetration spots or holes where it would have leaked fuel,” said Cassino.

The next expert to take the stand was Aaron Redsicker, a senior fire investigator with S-E-A, Ltd., whose goal was to figure out how the fire started, how it spread, and how it caused an explosion.

First, Redsicker said he had to take in the magnitude of damage and try to determine what could cause that.

“To do that, you have to determine materials that were at the site and evaluate that in what it would take to ignite said fuel,” said Redsicker

In his results, he determined Westmoreland overfilled the fuel tank at the South River Market with 800 gallons of gasoline.

“During the investigation, we looked for the remains of the cap and never could find that cap,” Redsicker testified. “Three witnesses had stated they saw fluid coming from that same area before the explosion.”

Aaron Redsicker testifies in Rockbridge County on Aug. 23, 2022. (Photo: WFXR News/Pool camera)

Once Westmoreland allegedly left the gas cap off, gasoline vapors were emitted into the air, according to the fire investigator.

The wind then pushed those dangerous gasoline vapors into the South River Market, where any appliance could have ignited and caused the explosion, Redsicker testified.

Redsicker added that the fire started in the pit that the above-ground storage tanks sat in.

After the prosecutors rested their case, the defense brought in two expert witnesses to debunk the prosecution’s claims.

The first of those witnesses was Dr. John Cignatta with Datanet Engineering.

According to the company’s website, Cignatta holds multiple certifications that ruled him an expert in this case, including civil-environmental engineering in both Maryland and Virginia, NACE corrosion specialist accreditation, American Petroleum Institute aboveground storage tank inspector accreditation, and MDE underground storage tank inspector certification.

Cignatta claimed Westmoreland did not cause the fire or the explosion, instead saying that the South River Market tanks were faulty because they were missing several types of safety equipment that are permitted by state and federal regulations.

For example, the fuel tanks did not have a drop tube to stop the gasoline from splashing into the tank.

“Displacement filling goes all the way down, four to six inches off the tank. This basically displaces the air out the tank, and we are not creating a gasoline cloud,” said Cignatta.

He explained that splash filling caused more gasoline clouds to emit into the air, which reportedly was not Westmoreland’s fault.

Cignatta also pointed out that the market’s ball valve was useless in stopping gasoline from overfilling.

According to Cignatta, the South River Market needed a trap door so vapors could not get out.

He also stated that there was never any evidence of a massive overfilling at the South River Market.

“Trap doors are required, and the trap door, you push it in and you can take your stick reading, pull it out, and it slams shut and seals,” Cignatta explained as he provided an equipment demonstration for the court.

The next witness was Dr. Rick Roby with Combustion Science & Engineering, Inc., who discussed his beliefs about what caused the fire at the South River Market and how the gasoline vapors got into the air.

Roby claimed the vapors could not have risen high into the air and then gotten into the gas station, adding that a backdoor to the store is what allowed the gasoline vapors to get in.

He also agreed with Cignatta that there was not a massive overfilling at the tanks that would have caused the fire to start.

The defense says they plan to rest their case by Wednesday, Aug. 24.