In the aftermath of a deadly shooting outside a party at a Southeast Washington apartment building, investigators searched for evidence that would positively identify one of their top suspects. But they never found it, and nobody came forward to name him.

As a result, authorities say, police couldn’t obtain the arrest warrant they needed to get the suspect, Orlando Carter, off the street. Days later, according to prosecutors, Carter drove a rented minivan while three of his friends opened fire on another group.

But Orlando Carter had been recognized at the party. Instead of telling authorities, Andre Morgan testified last week, he planned to avenge his dead friend — and is now charged with plotting to kill Orlando Carter.

Morgan’s testimony highlights the sprawling, complex nature of the five-defendant trial, in which Orlando Carter, 22, and four other men face murder and other charges for their alleged roles in a series of March 2010 shootings that killed five. The trial is to start its third week Monday in D.C. Superior Court.

Jurors have heard from witnesses facing felony charges and others reluctant to speak. The trial could last months, and more than 100 could testify.

Morgan, 21, testified that he was outside the apartment after the party with his friend Jordan Howe, 20, on March 22, when he saw Orlando Carter arrive in a car and hand a gun to his brother Sanquan Carter, 21.

Angry after Sanquan’s gold-colored bracelet disappeared, authorities say, the brothers and another man began shooting at the crowd. Howe was killed, and two others were hurt.

Morgan never planned to tell police, he testified. Instead, he told the jury, his first thought as he held Howe after the shooting was: “Kill Sanquan and Orlando.”

People familiar with the case say Morgan and several friends then planned an attack on Orlando Carter the next day — an attack Orlando Carter survived.

Authorities said Orlando Carter then orchestrated further retribution: a March 30 drive-by shooting in the 4000 block of South Capitol Street SE that targeted mourners who had attended Howe’s funeral. The drive-by, and the killing of a 17-year-old during a robbery minutes earlier, left another four dead and six injured.

Morgan’s testimony was one of last week’s key developments in the government’s case against the five men charged in the shootings. It also illustrates a common frustration for District authorities who often struggle to find cooperative witnesses. Police say many are distrustful of them, while some witnesses say they fear for their safety.

“It’s very frustrating,” a homicide detective familiar with Orlando Carter’s case said in an interview. “We like to close these cases as quickly as we can, but you have witnesses who refuse or have that ‘I’m not a snitch’ mentality.”

In addition to the Carter brothers, also on trial are Jeffrey D. Best, 23; Robert Bost, 23; and Lamar Williams, 23. Each is charged with dozens of offenses, including first-degree murder, conspiracy and assault. All five have pleaded not guilty.

After Howe was killed, Morgan testified, he and Howe’s 21-year-old half-brother, Marquis Hicks, plotted along with several of their friends to kill Orlando Carter. On March 23, Morgan testified, Morgan and Hicks found him and shot him twice.

The identities of the men who attacked Orlando Carter were not known to police until after Morgan and Hicks were charged with an unrelated armed robbery in July 2010, according to people familiar with the case. They were subsequently linked to Carter’s shooting and are charged with conspiracy to kill him, those people said.

Prosecutors have sealed the conspiracy cases against Morgan and Hicks.

Defense attorneys for the five defendants say Morgan falsely implicated the Carter brothers in an effort to curry favor with prosecutors in his own case. During his testimony, Morgan was repeatedly asked why he never told authorities that he recognized Orlando Carter at the party.

“I don’t know,” he replied.

Other witnesses have spoken of their reluctance to tell authorities what they saw on March 22, 2010.

“Where I’m from, you don’t talk to the police,” testified one 21-year-old woman who was a neighbor of Howe’s and said she was outside during the party shooting. But she also eventually identified Sanquan Carter to investigators.

Some witnesses have said they fear retaliation against them or their families. A 17-year-old who was shot in his left leg at the party lifted his pants, showing his scars. Several jurors flinched.

In sometimes-heated exchanges with defense attorneys, he repeatedly explained that he refused to go to a hospital because he was “nervous” and “scared” to talk to police.

Authorities have offered to relocate witnesses and their families to undisclosed locations “until things blow over,” the detective said, but some witnesses elected to remain silent.

Sitting in the courtroom, Nardyne Jefferies wondered whether the drive-by shootings, which killed her 16-year-old daughter, Brishell Jones, might not have happened if Morgan had stepped forward after the party.

“This could have been prevented if people stopped trying to take the law into their own hands and let people do their jobs,” Jefferies said. “Instead of letting the police do their job, they just make the situation worse where innocent people end up getting killed.”

The first person to name Orlando Carter as one of the shooters at the party was Nathaniel Simms, who pleaded guilty to a role in the party and drive-by shootings and has cooperated with authorities.