Oklahoma State Bureau of Investigation spokeswoman Jessica Brown said Wednesday two different caliber weapons were used to kill 13-year-old Taylor Paschal-Placker and 11-year-old Skyla Whitaker. Because two weapons were used, Brown says investigators believe there were two killers.
Brown declined to say what type of weapons were used.
The girls were discovered Sunday afternoon. The state medical examiner's office says each suffered multiple gunshot wounds to the head and chest.
Brown says a reward for information leading to an arrest in the case has been increased to $25,000.
No suspect or motive has been identified in the mysterious killings.
The bodies of Whitaker and Paschal-Placker were found on an isolated county road near a small town, about 70 miles south of Tulsa.
The pair, best friends who lived a few miles apart in an impoverished part of the community, had walked the road dozens of times for sleepovers. Family said they didn't have an enemy in the world.
Residents in this close community of 1,000 remained on edge knowing a murderer could be in their town.
"Believe it or not, I have never pulled any shades in my house and I keep my doors unlocked," said Dena Priddy, a teacher's aide at the public school the victims attended. "You just don't expect these things to happen here."
OSBI Special Agent Ben Rosser said it appears unlikely the girls were sexually assaulted. They were clothed when found and had been missing only a half hour. Full autopsy results were not back yet, he said.
Investigators were examining evidence, including tire tracks, shell casings, ballistics and shoe prints for any possible leads.
"We will bring all the resources we need to try to help in our investigation," Rosser said in an afternoon news conference.
But as of Tuesday afternoon, authorities had identified no suspects or persons of interest in the crime.
"Nobody we could put a finger on and say this guy's good for it," Rosser said.
Kevin Rowland, chief investigator with the state medical examiner's office, said the girls each suffered multiple gunshot wounds to the head and chest.
Rosser said the fact that the killings took place in such an isolated rural area leads investigators to presume a local person may have been involved in the crime.
Possibilities include that it was a random shooting, they had intended to meet someone or may have interrupted a crime that was occurring, Rosser said.
News that a killer, or killers, could still be in town sent shivers through many people in the small town. Locals are used to living in a place where everybody watches out for everybody else, your next-door neighbor may be two miles away and murders are something that happen in the big cities.
"I can't put it into words," said Jake Fenley, Skyla's basketball coach. "This doesn't happen in rural middle America."
For Priddy, that fear means taking extra precautions: "I got guns loaded," she said defiantly. She also refuses to let her 14-year-old daughter out of the house.
Tuesday morning, Taylor's uncle, Joe Mosher, drove up on the makeshift memorial at the place the bodies were found. Yellow crime scene tape had been torn away and thick patches of grass were matted down.
A rosary hung from a branch, and stuffed animals and a bouquet of flowers just beginning to wilt formed the grim reminder of innocence lost.
"It's the most tragic thing that I've ever seen," said Nell Mosher, Taylor's aunt. "They were just two precious little babies; they were good girls."