Kim Vuong, alongside family members, fourth from left, leaves a news conference in the District on March 25. Vuong’s husband, David Messerschmitt, was found slain at the Donovan Hotel in February. (Nikki Kahn/The Washington Post)

Just two weeks before she was arrested, Jamyra Gallmon told a good friend that she was not the woman whose face had been captured on a D.C. hotel surveillance camera about the time a lawyer was fatally stabbed there, the friend said Thursday.

“I literally asked her — I said, ‘Jamyra, you look like that lady in the camera,’ ” the friend said in a telephone interview. “She said, ‘Girl, no, that’s not me. I’m trying to go into the Army.’ ”

Police think that Gallmon was lying. And on Thursday — as the 21-year-old made her first court appearance on a first-degree murder charge — they revealed how she initially met up with intellectual-property lawyer David Messerschmitt and what she claimed led her to stab him.

Messerschmitt, 30, had posted on Craigslist, hoping for a sexual encounter with a man, according to police charging documents and officials familiar with the case. He and Gall­mon arranged a Feb. 9 meeting, and she would later tell detectives that she wanted to rob the lawyer, according to the documents.

In a fourth-floor room at the chic Donovan Hotel on Thomas Circle, something went awry. Gallmon stabbed Messerschmitt repeatedly, leaving him wounded in the abdomen, the groin and the heart, according to police.

David Messerschmitt was an intellectual-property lawyer with DLA Piper. (Courtesy of D.C. police)

Until Thursday, the case had been something of a mystery, and those who knew Gallmon at Forestville Military Academy in Prince George’s County said the arrest of the former high school basketball player and aspiring soldier made it only more confounding.

Brandi Gordon — who asked Gallmon in March whether she was the woman in the surveillance images being shown on TV — said that Gallmon was a reliable friend and that she doubted she killed anyone.

“It’s just not settling to me that she killed somebody,” Gordon said. “It probably was a coincidence that she was there.”

Gallmon’s defense attorney said in court Thursday that Gallmon had no criminal record, and friends and a former coach said they could recall no problems with her. The only issue that showed up in public records was a minor financial matter. On Feb. 24, a few weeks after Messerschmitt was killed, Gallmon’s landlord took her and a roommate to court for back rent, and the next month they were ordered to pay $1,860.

On Wednesday, Gallmon was charged by D.C. police with first-degree murder in the February killing of Messerschmitt, although police revealed few details at the time. On Thursday, in urging a judge to keep Gallmon confined, Assistant U.S. Attorney Shana L. Fulton called the suspect dangerous and her crime planned.

“She set this up, and she could do this again in the future,” Fulton argued.

D.C. police earlier released this video of a person of interest in the fatal stabbing of 30-year-old lawyer David Messerschmitt. Police made an arrest in the case this week. (YouTube/DC Metropolitan Police Department)

Matthew Davies, Gallmon’s defense attorney, said the case was one of “imperfect self-defense.” Davies argued that when Messerschmitt allegedly grabbed her arm and became aggressive with Gallmon, she had a flashback to a previous incident and reacted.

Magistrate Judge Renee Raymond ultimately ordered Gall­mon jailed until an April 10 hearing, citing her alleged orchestration of the meeting, the severity of Messerschmitt’s wounds and a knife that was found at Gallmon’s home.

Police alleged in charging documents that Messerschmitt began corresponding with Gallmon the afternoon of Feb. 9 and that the two arranged to meet in Room 400 of the Donovan Hotel between 7 p.m. and 7:30 p.m.

Police have said Messerschmitt texted his wife about 7:30 p.m., telling her that he would return to their Capitol Hill home in about an hour. That is the last time his family heard from him. He was found dead Feb. 10.

According to the charging documents, Gallmon told detectives that she went to the room to rob Messerschmitt and found the door open when she arrived. She said she went inside, but Messerschmitt “did not know she was in the room until she turned to walk out,” according to the documents.

Gallmon told detectives that Messerschmitt then “grabbed her arm causing her to flashback to a memory of when she was assaulted,” according to police charging documents.

She acknowledged that she pulled a knife from her sweatpants and stabbed the lawyer repeatedly, including at least once after he fell to the floor, according to the documents.

Gallmon took Messerschmitt’s cash and his Metro card, according to court papers.

It is possible that Gallmon’s account is not entirely accurate. According to police charging documents, detectives found zip ties on Messerschmitt’s fingers that seemed to have been made into handcuffs. Gallmon admitted to bringing zip ties into the room but denied using them, according to the documents. Davies said his client’s statement was coerced. A search warrant in the case shows that police also found lubricant and condoms in the room, among a host of miscellaneous items.

At some point, police learned that Messerschmitt had posted a Craigslist advertisement — “soliciting responses from other men” — and found correspondence between him and an account linked to Gallmon, according to police charging documents. They connected Gallmon to that account in part by using a cellphone number and e-mail address connected with it, according to the documents.

On Thursday, D.C. Police Chief Cathy L. Lanier asked anyone familiar with the e-mail address to come forward. “We want to know if there are any other victims of crimes out there connected through this e-mail,” Lanier said.

Messerschmitt’s wife — Kim Vuong — declined to be interviewed for this article, but in a statement, she thanked D.C. police for their “hard work and continued diligence.”

“I have faith that the police and the courts will bring justice to David and all who loved him,” she said. She said she would not comment further “until his case is resolved.”

Messerschmitt grew up in suburban Cincinnati and attended Boston University School of Law and Ohio State University, where he met his wife. He worked for a law firm in Chicago and two in Washington, then started at the international firm DLA Piper last year.

Gordon, 19, who knew Gall­mon from high school, said she did not think that Gallmon knew Messerschmitt. She said that when she first saw news of the case on TV, she remarked to her sister that Gallmon looked like the woman in the surveillance footage, and she asked Gallmon about it in March when they spoke on Gordon’s birthday.

Gallmon, she said, denied that it was her, and their phone call gave her no reason to suspect anything was amiss. As she does every year, Gordon said, Gallmon sang her a birthday song; this year, it was Avant’s “My First Love.” Gordon said Gallmon talked about going to the movies and meeting with her Army recruiter.

“She was acting so normal,” Gordon said.

Gordon said she now believes that the woman in the surveillance footage was Gallmon, although she is skeptical of the police allegations.

Others who knew Gallmon also said they were surprised by her arrest. Vincent McDuffie, her former basketball coach at Forestville Military Academy, said Gallmon was “very low-key, very mild-mannered.” He said Gallmon — a forward and center who aspired to play college basketball until she tore her ACL late in her high school career — was a consummate team player who seemed to get good grades. School officials said Gallmon graduated from Forestville in June 2011.

“I’m just shocked, because that was never part of the personality that she exhibited in school,” McDuffie said.

McDuffie said he talked to those who knew Gallmon in recent months and that they said she was living on her own and holding down a job — possibly in security.

Melvin Key, chief executive of MVP Protective Services, said that Gallmon worked for his company for two months and left in December 2014, saying she wanted to become a police officer.

“She was well-spoken, determined and focused,” Key said.

At her court hearing Thursday, Gallmon, wearing a red hooded jacket and black sweatpants, stood with her wrists and waist in iron shackles. About a dozen of her relatives and friends sat in the courtroom; several broke into tears. The family declined to comment after leaving the courthouse.

Lynh Bui, Mary Pat Flaherty, Peter Hermann, Jennifer Jenkins, Dan Morse, Rachel Weiner and Clarence Williams contributed to this report.