The woman portrayed as the brave survivor of a brutal attack at a Bethesda yoga store has now been charged with killing her co-worker.

The victim-turned-suspect was found inside the Lululemon Athletica store bound and bruised, and she convinced detectives that two men in ski masks and gloves raped and beat her and her fellow employee.

But it was all a lie, police now say.

Brittany Norwood, 27, was charged late Friday with murder in the March 11 death of Jayna T. Murray, 30, who was beaten and stabbed.

Montgomery County Police Chief J. Thomas Manger said that there is no evidence there were any sexual assaults at all and that Norwood very likely inflicted her own injuries and tied herself up.

Norwood’s tale, which captivated the region and had shoppers and merchants along Bethesda Row in fear, began to unravel as detectives looked at the evidence.

“When the investigation began, detectives had only the story of Ms. Norwood to go by,” Manger said. But “the forensic evidence and the physical evidence was not supporting what Ms. Norwood had told us.”

The suspect’s story terrified residents and merchants in downtown Bethesda, an area of restaurants and high-end stores that has long been considered one of the safest spots in the region. Stores moved to install security cameras. Private security guards escorted workers to their cars. Average citizens began asking clothing stores if they’d sold ski masks to anyone suspicious. A reward of more than $150,000 was lined up to catch the intruders.

But in the end, Norwood, who went to high school in Washington state and college in Long Island, N.Y., couldn’t keep her story going, police said.

Assistant Chief Drew Tracy said there were some inconsistencies from the beginning, but detectives chalked them up in part to a stressed victim.

One of the unanswered questions, Tracy said, involved Norwood’s wounds. The wounds were superficial, compared with Murray’s. Investigators wondered why she didn’t leave the store before another employee opened it the next morning.

A big break in the case was provided by evidence found in Murray’s car, Manger said. Norwood had gotten into Murray’s car, which had been parked in front of the store, and drove it to a parking lot a few blocks away off Wisconsin Avenue, the chief said. He declined to specify what was found in the car.

Manger also said detectives found only two sets of bloody shoe prints in the Lululemon store. One set belonged to Norwood, he said, and the other came from shoes that belonged to the store and were found at the crime scene. So that cast doubt on the story about intruders, police said.

In addition, employees of an Apple store next door said they heard two women arguing the night of the killing, Manger said.

Tracy and Manger both said that detectives had little choice but to believe Norwood’s story at first.

“Victims of sexual assault, you have to take their story as truthful,” the chief said.

When police began their probe, Manger said, detectives aggressively investigated Norwood’s story. They examined surveillance cameras from the area, searching for signs of the mysterious attackers. Tips came in, and officers even followed a man they thought might be a “person of interest,” Manger said.

“Four days ago I really believed this was a random crime of opportunity,” Manger said. “It’s a tragic case.”

At first, Norwood appeared to be a victim, along with Murray.

About 8 a.m. last Saturday, a worker at Lululemon arrived for work and heard a noise in the back of the store. She retreated and asked a man outside to go in. He found a horrific, bloody crime scene, according to officials.

Norwood was tied up. She was taken to a local hospital, where detectives spoke to her. Police officials began describing the case to reporters, based largely on her statements.

By Monday, officials had established a timeline of what they believed had happened:

At 9:45 p.m., after closing the store, Norwood and Murray left. But Norwood called Murray to say she had left her wallet in the store and asked if Murray could meet her there, police said. They went inside, closely followed into the store by two masked men, who attacked them.

By Tuesday, what appeared to be a promising lead that tracked the suspect’s original story had dried up, according to a police source. At the same time, analysis of forensic evidence was starting to come in.

For Bethesda Row merchants, the arrest was a relief.

“Everybody feels like they can breathe,” said Golnaz Fiez, general manager of Assaggi Restaurant Mozzarella Bar on Bethesda Avenue, a few doors down from the yoga store.

The restaurant’s business was down 50 percent this week, said Giovanni Medrano, a manager at the restaurant. Foot traffic along the road has been light and many businesses have closed early because employees were nervous, he said.

“It brings closure to the case,” Medrano said. “People have been very, very apprehensive. Very, very nervous.”

Staff writers Dana Hedgpeth, Ed O’Keefe and Clarence Williams and researchers Jennifer Jenkins and Julie Tate contributed to this report.