By Jason Hanna and Darran Simon, CNN

(CNN) -- South Carolina fifth-grader Raniya Wright -- the girl who died last month after a fight at her elementary school -- died of a blood-vessel rupture in the brain stemming from a birth defect, and there's no evidence the fight contributed to her death, a prosecutor said Friday.

The death of Raniya, 10, will be attributed to natural causes in a report next week, and no criminal charges will be filed in the case, district solicitor Duffie Stone told reporters Friday.

"There was no evidence of trauma on or inside the body of Raniya Wright that would indicate that any fight in any magnitude contributed to her death," Stone said at a news conference, announcing the initial results of the investigation into the young girl's death.

Stone said he made the determination after pathologists and other doctors conducted postmortem tests at the Medical University of South Carolina, where Raniya died March 27.

Raniya was involved in a "five- to 10-second slap fight" with another student in a classroom at Forest Hills Elementary in Walterboro on March 25, and a teacher separated them, Colleton County Sheriff R.A. Strickland said Friday. Raniya had no sign of and spoke of no injury, but complained of a headache about 10 minutes later at the principal's office, he said.

Authorities have said she then lost consciousness, and medics took her to a local hospital. She later was transferred to the Medical University of South Carolina in Charleston, where she died.

Raniya's birth defect caused headaches for months, prosecutor says

Raniya's brain had an "arteriovenous malformation," or AVM -- a tangling of vessels connecting arteries and veins, Stone said.

The condition disrupts normal blood flow, meaning surrounding tissues may not get enough oxygen, and affected vessels can rupture, the Mayo Clinc says.

It apparently caused headaches that the girl recently sought treatment for; the rupture was ready to take place "just about any time," and the "fight did not have anything to do with her passing away," Stone said.

Stone said Raniya had visited a doctor at least six times relating to headaches since February 2017, including 13 days before the fight.

"The headaches are a manifestation" of "this type of condition," he said, adding: "It was a matter of time."

When reporters asked whether the fight could have affected her condition, including whether stress led to the rupture, Stone said: "They (pathologists and others who examined Raniya) had no signs whatsoever that the fight had anything to do with it."

Every year, about four in 100 people with an AVM will have a hemorrhage, the American Association of Neurological Surgeons says. Each hemorrhage poses a 15% to 20% risk of death or stroke, the association says.

Investigators appear at odds with Raniya's mother over students' histories

Authorities appear to be at odds with what Raniya's family has been saying about what led to the March 25 fight and the degree to which the students had been antagonistic previously.

"Petty children's things" appeared to lead to the slap fight in the classroom, sheriff's Maj. Jason Chapman said at the news conference.

Chapman cited interviews with students -- including a statement from Raniya sometime before she died. Chapman didn't say when Raniya's statement was taken.

"It did not appear to be anything that transpired prior to that date or anything that had grown" from a previous incident, Chapman said. "Speaking with teachers, there's not any (other) documented incidents" between the two children.

But speaking to "Good Morning America" earlier this month, Raniya's mother, Ashley Wright, said Raniya's friends told her that a bully had been baiting the 10-year-old into a fight and caused her to hit her head on a bookshelf before she died.

"She would just always come home saying this one girl was picking on her," Ashley Wright told GMA on April 8. The complaints had been ongoing since the fourth grade, Wright said.

Stone, the prosecutor, said he met with Raniya's family Friday morning and explained his office's findings before he announced them at the news conference.