"There were no witnesses, so we do not know whether she fell or stumbled," Pasquarello said. "It could be that she fell and was then struck by the car."

Investigators determined that there had been no criminal wrongdoing based on interviews with the driver and an analysis of the accident scene.

"There was no evidence presented that the operator of the motor vehicle was negligent," Pasquarello said. "It was a stormy evening and [Palmer-Sherman] was crossing the street outside of a crosswalk."

"There did not appear to be any speeding or criminal intent, and the operator's statements were consistent with what investigators found," he added.

Pasquarello has met with Palmer-Sherman's parents several times over the past two months to brief them on the investigation.

He expressed his concern that not charging the driver would be difficult for Palmer-Sherman's family. He said he believed her parents would likely file a civil suit against the driver.

Palmer-Sherman, who died from her injuries on Dec. 22, was a resident of Pforzheimer House and a history and literature concentrator.

She was also active in Harvard Hillel and a graduate of Horace Mann High School in Riverdale, N.Y., where she was involved in the school's drama department.