A woman who was dropped off “unconscious and unresponsive” at a Loudoun County medical center by Washington Redskins safety Montae Nicholson and a friend in November died of an accidental overdose of fentanyl, authorities said a Virginia medical examiner has ruled.

The Loudoun County Sheriff’s Office said Monday that the investigation into the death of Julia Crabbe, 21, of Reston, remains ongoing and that detectives are still trying to determine the source of the drug that killed her. No charges have been filed.

Nicholson and a friend drove Crabbe to the Inova Emergency Room-Ashburn HealthPlex around 1:30 a.m. on Nov. 14, according to Nicholson’s attorney. She was pronounced dead a short time later.

Mark Dycio, Nicholson’s attorney, has said Crabbe, Nicholson and some friends had gone out for dinner earlier that evening, before returning to Nicholson’s Ashburn home. Nicholson later told Crabbe’s brother that some people were playing video games on the lower level of his home when Crabbe went upstairs to use the bathroom, according to Crabbe’s family.

The people in Nicholson’s home heard a thump and went upstairs to find Crabbe on the floor of the bathroom, according to Crabbe’s family. The door of the bathroom had to be forced open.

A search warrant filed in Loudoun County Circuit Court said Nicholson’s friend, Kyle Askew-Collins, called an unnamed person during the early-morning hours of Nov. 15 to say Crabbe was foaming at the mouth and was believed to be overdosing.

The unnamed person was en route to Nicholson’s home to help Crabbe when Askew-Collins called to say they were taking Crabbe to a hospital. The search warrant states surveillance cameras at the HealthPlex captured Nicholson and Askew-Collins arriving in a black Nissan Armada.

Investigators found pills, marijuana and foil with residue on it in Nicholson’s home, according to the search warrant. Investigators did not detail who the drugs belonged to or where they were found.

“Montae Nicholson is extremely saddened at the tragic loss of this beautiful woman,” Dycio said in a statement Monday. “The drug epidemic has such a wide and destructive path leaving friends and family to suffer the loss of the ones we love. We pray for Julia’s friends and family.”

Crabbe’s family did not immediately return a request for comment.