Gabriela Jose Lopez Hernandez moved to the District from her native Venezuela when she was in her early 20s, landed a job as a paralegal for an immigration lawyer and, in the fall of 2005, took up dance lessons at the Adams Morgan nightclub Meze.

Blanca Ortiz, nearly 20 years older, was learning the tango at the same nightclub. They met and, during the next year, became close. But how close? And did the nature of their relationship lead to Lopez’s violent death in her Kalorama Triangle apartment?

Prosecutors and lawyers for Ortiz, who is accused of killing Lopez, will soon debate those questions in a District courtroom. Lopez, 29, was found dead in her efficiency apartment’s bathtub on Jan. 28, 2007, stabbed more than 15 times and the back of her head showing signs of trauma. Authorities say Ortiz killed the woman she called “Gabby” during a violent rage, then cleaned the crime scene with bleach and fled.

D.C. authorities charged Ortiz in Lopez’s slaying in 2008 after she had returned to her native Argentina. After discussions with Argentine officials, Ortiz was extradited to the United States last year. Her trial on charges of first-degree murder is scheduled to begin this week in D.C. Superior Court before Judge Ronna L. Beck.

Prosecutors have little evidence connecting Ortiz, 47, to Lopez’s death. There is no DNA linking Ortiz to the crime, investigators have not recovered a weapon and they have no eyewitnesses.

They do, however, have a security video that shows Ortiz entering and leaving Lopez’s apartment about the time medical examiners say Lopez was killed. In early interviews with detectives, Ortiz admitted being at Lopez’s apartment that day but gave differing accounts of how long she was there. And when detectives searched Ortiz’s apartment days after Lopez’s body was discovered, they couldn’t find a blue coat she was wearing in the video — perhaps a sign, they thought, that she discarded it after killing Lopez.

The nature of the relationship between Ortiz and Lopez will likely be central to the trial, with prosecutors and defense lawyers expected to detail disparate characterizations of it.

Authorities say the friendship grew intimate, and Ortiz killed Lopez in a rage. They are expected to use photographs showing the women behaving affectionately and the words of Lopez’s former boss to bolster that argument; they also call the stabbing a classic “crime of passion.”

“It appears someone was acting out of anger and emotion by the excessive number of wounds,” Lt. Robert Alder, commander of the D.C. police homicide branch, said in an interview.

But Ortiz denied a love affair in interviews with police, and her lawyer surmises instead that the killer could have been one of the men in Lopez’s life. The sides disagree about whether the women lived together in Lopez’s apartment: Some of Ortiz’s clothing and prescription medicines were found there, but she told police only that she sometimes spent the night and watched the apartment when her friend was away.

Ortiz’s lawyer, Andrew Jezic, argues that there is more surveillance video that could show the killer. In court filings, Jezic has petitioned the judge to order prosecutors to produce additional surveillance video for 12 to 24 hours before and after the estimated time of Lopez’s death.

“There are several other people that were either very close with her or romantically involved with her that may have had some serious conflicts with her,” Jezic said in an interview.

According to a transcript of Ortiz’s interrogation by D.C. detectives, Ortiz said Lopez had a couple of “friends with benefits” — men who weren’t boyfriends, but who accompanied her to parties and with whom she had sex.

In a court filing last week, Jezic said he planned to present alternative theories of how Lopez might have been killed during the trial by discussing three men who could be responsible: an ex-boyfriend of Ortiz’s and another of Lopez’s, plus Lopez’s former boss, the immigration lawyer.

“This notice does not constitute any representation that there is any particular level of proof regarding any of these individuals at this time,” Jezic wrote in the filing. “This notice simply mentions those people, among those known or unknown, who may have had a romantic or other close relationship with the victim and who may have had some conflict with the victim.”

During her first interview with detectives, conducted three days after Lopez’s body was found, Ortiz said that she had been in Lopez’s apartment for about an hour on the morning authorities think the woman was killed. Days later, during a second interview, she said she had been there only for a few minutes.

Ortiz said Lopez had agreed to accompany her to an appointment, but when she arrived at the apartment, Lopez said she could not go. Ortiz said she used Lopez’s bathroom and left. One of Lopez’s former boyfriends was in the apartment at the time, she said.

Ortiz’s journey to Washington is complex. According to court papers, Ortiz told detectives she was one of eight siblings and graduated from a college in Buenos Aires. She traveled extensively before moving to France, where she taught Spanish in a French school. In 1996, Ortiz said, she married a French architect, and the couple moved to Saudi Arabia, where he worked.

She said she moved to the Washington area to study English in 2005; her husband remained in the Middle East. She found an apartment in Silver Spring and took classes at the Lado International Institute and Kaplan University, she told detectives.

In Washington, Ortiz told detectives, she dated a man about 10 years her junior who had an alcohol problem and was sometimes violent. That man was a source of conflict between Ortiz and Lopez, according to a person familiar with the case who spoke on the condition of anonymity because the case was heading to trial. On several occasions, Lopez told Ortiz to leave the man.