Oklahoma police said Thursday that they've interviewed a witness who drove by two girls minutes before they were shot dead along a country road.
"We can let you know — and the shooters out there — that we do have a witness that was there shortly before the shooting," Special Agent Ben Rosser of the Oklahoma State Bureau of Investigation said at an afternoon news conference.
His agency has interviewed the male witness and believes his story to be credible, Rosser said.
Rosser said it appeared that the gunman or gunmen used two guns to kill both Taylor Paschal-Placker, 13, and Skyla Whitaker, 11, on Sunday on County Line Road in Weleetka, Okla.
"Each girl was shot with both calibers," Rosser said. "In other words, if we have two shooters then each of the shooters shot each girl — if we have two shooters."
Rosser stressed that it still isn't known whether there were multiple shooters, and investigators still don't have a motive, suspects or persons of interest in the case. Police returned to the scene of the crime Thursday to comb a riverbed and the area where the girls were found.
"What is probably plausible is if they saw something they shouldn't have," Jessica Brown, a spokeswoman for the Oklahoma State Bureau of Investigation, told FOX News.
But Rosser downplayed talk in the community that the girls' murder had something to do with a methamphetamine problem in the area.
"It's not a drug haven down there, and I don't have any reason to believe it was," he said. "But you never know, somebody could have stopped to shoot up on dope or something. You just never know."
Skyla's grandfather, Jimmie Farrow, had told the Associated Press that meth use had gotten bad in the area.
"You think you're safe anywhere, but you're not. All the thugs is moving out here, too," Farrow told the AP. "It's a whole new ballgame."
Rosser said his bureau and the Okfuskee County Sheriff's office were looking into past burglaries, carjackings, sexual assaults and complaints of shots fired in an effort to find a possible suspect.
"I just think that until we identify these guys and pick them up, I think anybody in that area should have some caution about their outdoor activities," Rosser told FOX News.
The girls were found dead on Sunday just a few hundred yards from Taylor's home near a bridge she often walked to for exercise.
An autopsy found the girls died of multiple gunshot wounds to the chest and face, Chief Investigator Kevin Rowland of the Oklahoma Chief Medical Examiner's office told FOXNews.com.
Rosser has not said how many times the girls were shot.
Taylor's grandfather, Peter Placker, found the girls clothed in T-shirts and shorts just 20 to 25 minutes after they left Taylor's house. That short window is among the reasons investigators think the girls were not molested by their assailants, though lab work is pending.
In addition to the ballistics tests, police were examining shoe and tire prints, shell casings and any computer correspondence the girls made.
Police said the crime scene's isolation made it seem more likely that locals killed the girls. Rosser said family members and friends are not suspects.
A $25,000 reward for information leading to the arrest and conviction of the killer or killers has grown, but Rosser didn't say by how much.
Meanwhile, mourners left stuffed animals and flowers at the crime scene as their families prepared to lay them to rest.
A funeral will be held for Taylor at 10 a.m. Friday at the Dewar First Baptist Church. Skyla's funeral will begin at 2 p.m. Friday at the First Baptist Church in Henryetta.