Tests on bullet fragments definitively link only two of 11 shootings along a five-mile stretch of highway circling the city, authorities said Saturday.
Chief Deputy Steve Martin of the Franklin County sheriff's office said two fragments were "a definite match," but not enough was recovered from similar shootings to verify further matches.
On Friday, police said a Nov. 25 shooting that killed a 62-year-old woman — the only person hit by a bullet — wasn't accidental and is linked to at least one other case. The string of highway violence began in May, but most of the shootings have taken place in the last seven weeks.
At a news conference, Martin said one or more people are deliberately targeting drivers. But Martin refused to use the word "sniper" concerning the gunman.
Martin said the term sniper evokes an image of someone with military training lying in wait in the woods while wearing camouflage. The highway shooter could be mobile, he said.
A task force investigating the shootings has received 250 tips, many naming suspects, Martin said. Police have gone out to interview people named in tips, but have not taken anyone into custody for questioning, he said.
The shootings, all on or near a southern section of Interstate 270, took place at different times of day, piercing trucks, cars, vans and pickups, shattering windows and flattening tires.
Gail Knisley, who was shot and killed Tuesday, was buried Saturday in her hometown of Washington Court House, about 40 miles southwest of Columbus.
Martin declined to discuss the type of weapon used, saying it could harm the investigation.
"We have some ideas, but we're not going to discuss those issues," he said.
Extra patrols have been assigned to the section of the highway, which is thick with brush and woods in some parts and bordered by houses, scattered industry and open fields in others.
Ohio's gun deer-hunting season opens Monday, so the public shouldn't be alarmed at the sight of people with shotguns, Martin said. He asked hunters to be alert to anything suspicious.