Charleston Police Department van

Police are asking for the public's help locating this van and its occupants, who they believe witnessed a homicide on Jan. 30, 2018 on the westbound Meeting Street on-ramp to Interstate 26. Charleston Police Department/Provided

Charleston police released two new photographs Friday night of a van that was seen at the scene of a homicide in downtown this week.

Investigators believe the van may have driven past the westbound Interstate 26 on-ramp from Meeting Street Tuesday night moments before 48-year-old North Charleston resident Dominique Sheppard was fatally shot.

"Investigators are attempting to identify this vehicle and its occupants, who may have witnessed a portion of the incident," police said.

It is described as a "light colored, full-size panel van with what appears to be a ladder rack on top," and windows on both the front and rear doors.

Officers responded at 11:38 p.m. to the on-ramp after a passerby called saying they saw a silver Chevrolet Malibu stopped on the side of the road and a man lying on the shoulder, according to an incident report.

The passerby told authorities they saw another person in the car's driver's seat, the report said.

Investigators believe the victim's vehicle turned left from Meeting onto the ramp and that the victim "became involved in some type of altercation," shortly after, police said.

The Malibu was unoccupied by the time officers arrived at the scene and was idling about 50 feet behind the victim, "partially pulled onto the shoulder of the on-ramp," the report said.

Sheppard's death is the first homicide within Charleston city limits in 2018 and the second in the tri-county.

Anyone with information about the homicide is asked to contact the Charleston County Consolidated 911 Center at 843-743-7200 or Crime Stoppers at 843-554-1111.

Reach Gregory Yee at 843-937-5908. Follow him on Twitter @GregoryYYee.

Gregory Yee covers breaking news and public safety. He's a native Angeleno and previously covered crime and courts for the Press-Telegram in Long Beach, CA. He studied journalism and Spanish literature at the University of California, Irvine.