A memorial was set up at the location where Julian Dawkins was shot and killed by an off-duty Arlington County sheriff deputy at the corner of Lynhaven Drive and Evens Lane in Alexan dria, seen here on May 23, 2013. (John McDonnell/The Washington Post)

At 12:39 a.m. May 22, Tanea Bynum text-messaged her boyfriend.

“You need to stop drinking!!!” she wrote to Julian Dawkins, according to a record read in court Tuesday. They had been at a celebration in Alexandria for a cousin who had been drafted by the Washington Mystics, and Bynum had left early.

“You’re drunk and your cousin needs you in the morning,” Bynum said in her message.

Bynum testified that she and Dawkins had planned to take his cousin to an early medical appointment. After messaging Dawkins, Bynum said, she called him, and he sounded “irritated.” He told her some guys were hassling him, strangers who weren’t from the neighborhood. He hung up.

Bynum called Dawkins again and texted again, but got no reply, she said Tuesday. So she texted another of Dawkins’s cousins and told her to find him and tell him that it was time to leave. The next call Bynum received was from the cousin, telling her that Dawkins had been shot.

Craig Patterson (Alexandria police)

Craig Patterson, 44, an Arlington County sheriff’s deputy, is charged with first-degree murder in the shooting, and his trial began Tuesday in Alexandria Circuit Court. The testimony offered a new glimpse into the last few minutes in the life of Dawkins, a 22-year-old driver for PBS “NewsHour.”

There is no dispute over whether Patterson, who was off duty that night, shot Dawkins on Lynhaven Drive. In a chilling 911 call played in court, he told a dispatcher, “I just had a young man pull a knife on me, and I shot him.”

At issue is whether the killing was justified. Prosecutors have argued that after an argument on the street, Patterson went to get his gun, returned and killed the younger man without justification. Dawkins did have a knife, but it was found folded and clipped in his pocket where he died, prosecutors have said in court.

Defense attorneys have countered that their client acted in self-defense. They contend that Dawkins was intoxicated and suggest that he was threatening on the night of his death.

In court Tuesday, witnesses described the argument that led to Dawkins’s death. Sheronda Brown lives next door to Dawkins’s aunt, who hosted the party. She told jurors that she heard Dawkins arguing with a man who yelled: “I’ll be back. You best believe I’ll be back.”

At an earlier hearing, Willie Sydnor testified that Dawkins and Patterson, who was staying with a nephew in the neighborhood, seemed to have been arguing about which of them had a right to be there. Sydnor said he heard Patterson say, “What you doing in this territory?” and Dawkins responded, “This is my block.” Sydnor said he saw Dawkins chase Patterson briefly.

In his 911 call, Patterson told the dispatcher that Dawkins “approached me about being in his neighborhood, telling me it was his neighborhood.”

A forensic toxicologist testified Tuesday that tests showed Dawkins had smoked marijuana about five or six hours before the shooting and that he had been drinking alcohol for several hours.

Dawkins’s mother cried as a medical examiner described the path the bullet took through her son’s chest, piercing his left lung and aorta and severing his spine.

Neighbors have described Dawkins as an outgoing young man who was well-known in the area and well-liked. “He was our balm and our rock,” Gwen Ifill, a “NewsHour” senior correspondent, said at his funeral, according to a transcript.

The day after the shooting, Patterson visited the home of ex-wife Najah Patterson and collapsed crying, she testified at a July hearing. More than a dozen employees of the Arlington County sheriff’s office came to that court appearance to show support for their colleague, a 17-year veteran of the department. He has been on unpaid administrative leave since he was charged.

Get updates on your area delivered via e-mail.