New court documents in the Lululemon murder case describe a horrific attack inside the Bethesda yoga store, detailing how employee Jayna Murray was struck in the head again and again as she fell to the floor.

The assailant, who prosecutors say was co-worker Brittany Norwood, trapped Murray in a narrow hallway leading to the store’s back door the night of March 11, authorities said.

“Repeated blows in this confined space [occurred] during a transition from standing, to kneeling or crouching, to a position on or near the ground as the beating progressed,” a forensic specialist in blood-spatter evidence wrote in a report filed with the court.

Murray’s body was found the next day, face down, in the hallway, with a large pool of blood next to her head and neck, according to the report. Prosecutors have said she was stabbed, beaten with a weapon and left with a ligature around her neck. Her skull was crushed, and her spinal cord severed.

The brutal nature of the attack was a big factor early in the investigation. For seven days, Norwood told detectives that after closing time, two masked men slipped in and attacked and sexually assaulted her and Murray. Norwood was discovered inside a bathroom, tied up, with blood on her face. She is 5-foot-2 and 120 pounds, and detectives originally thought she was a victim.

But as they sifted through forensic evidence, police say, Norwood’s story fell apart. They said she attacked Murray then staged her own injuries.

As the case heads for an October trial, prosecutors are prepared to call blood-spatter specialist William Vosburgh to testify. He would tell jurors how blood on the store walls can help explain how Murray was attacked.

Norwood’s attorneys have asked a judge to prevent Vosburgh’s opinions from being used in the trial. “Mr. Vosburgh’s opinion testimony, based on bloodstain pattern analysis, should be excluded because his conclusions are not based on valid and reliable scientific methodologies,” attorneys Douglas Wood and Christopher Griffiths wrote.