Brittany Norwood lost control the night she killed her co-worker at a Bethesda yoga store, her defense attorney said Wednesday as the high-profile trial began.

Norwood, 29, and co-worker Jayna Murray, 30, got into a “horrific fight” that March night, Douglas Wood told jurors during his opening statement. He said that Norwood grabbed makeshift weapons from the store and that Murray was dead within 15 minutes.

“Ladies and gentlemen, Brittany Norwood lost it,” Wood said. “There’s no doubt about that. She lost it. She lost control.”

Wood’s explanation Wednesday marked the first time Norwood’s legal team has laid out her defense in the murder case. The admissions reflect overwhelming evidence tying Norwood to the killing. The defense’s hope: that jurors conclude that things started as a fight between the women and that Norwood never had the intent required for a first-degree-murder conviction.

The distinction could make a big difference. In Maryland, premeditated murder carries the possibility of life with no chance for parole. Second-degree murder carries a maximum of 30 years in prison with a chance for release after 15 years.

Montgomery County State’s Attorney John McCarthy described what he characterized as a brutal and prolonged attack that left hundreds of wounds. He told jurors in his opening statement that Norwood cracked Murray over the head with a foot-long metal bar that was part of a merchandise rack, chased her through the store and kept pounding on her as she fell to the floor.

Norwood apparently used a hammer, a wrench, a knife and a peg used to hold up a mannequin in the attack, he said.

On top of that, the prosecutor said, Norwood tried to strangle Murray.

“This is the rope,” McCarthy said, holding up the bloodstained item. “And you can see the hair, Jayna’s hair, hanging on the rope.”

At one point on that night, he said, an employee at the Apple Store next-door to Lululemon Athletica heard a woman’s voice cry out:“Oh God, please help me.” A worker pounded on the wall but did not take further action, he said.

In the end, Murray suffered at least 322 wounds, 107 of which were defensive wounds inflicted as she tried to use parts of her body — including her hands and forearms — to shield herself, McCarthy said. The medical examiner who performed the autopsy said she had never seen so many defensive wounds, he told jurors.

“On March the 11th of this year, she savagely ended the life of Jayna Murray,” McCarthy said. “Today we begin the process of holding her accountable for the crime she committed . . . first-degree, premeditated murder.”

Under Maryland law, premeditation can happen within seconds. The longer McCarthy is able to draw out the attack in jurors’ minds, the stronger his case becomes.

“The defense has a very tough battle on their hands,” said Victor Del Pino, a defense attorney and former Montgomery prosecutor who watched the proceedings and is not involved in the case.

Norwood’s defense lawyers tried to plant the idea that she had lost her ability to think that night. “What they’re trying to do is minimize the culpability, based on her state of mind,” Del Pino said.

McCarthy anticipated such a defense and began the trial by quickly drawing a distinction between Murray and Norwood. He called the former an “extraordinary young woman” pursuing two master’s degrees from Johns Hopkins University at the time of the crime. The first photo he showed jurors, projected on a large screen, was of Murray’s smiling face.

The second photo was of Norwood, with a dour expression, taken on one of the nights police questioned her.

Families of both women, including their parents, sat in the third row of the courtroom separated by the middle aisle. The trial is expected to last about eight days.

McCarthy, a former high school teacher who has prosecuted more than 100 murder trials, slowly walked jurors up to the morning of March 12, when Murray was found dead inside the store and Norwood, discovered tied up in a bathroom. Norwood would later tell detectives they had been attacked by masked men who slipped into the store after closing.

Police at first considered Norwood a victim but discovered that her story was part of a detailed coverup, McCarthy told jurors.

Norwood staged a robbery and tossed mops, brooms and chairs around the room, he said. McCarthy said she cut Murray’s pants to make it appear that she had been sexually assaulted. And he suggested that she used a pair of men’s shoes to track blood around the store — trying to make it appear that a large man had been there.

But Wood said Norwood wasn’t cunning after the killing, as McCarthy maintained.

“Things that Brittany Norwood did after this were totally inept,” said Wood, who has been a defense attorney in about 75 murder cases. “They show someone, we submit, who got involved in a nightmarish situation, a nightmare, and had this sort of imagination, or this explanation of what happened, and it was full of holes because there was no premeditation, deliberation and willfulness.”