Maryland State Trooper Wesley Brown could have arrested the disorderly Applebee’s patron instead of throwing him out of the restaurant, prosecutors said. The man had tried to punch another officer and then ran from the scene. Even the other officer thought it might be best to bring him in, prosecutors said.

But Brown had told his partner that night in June 2010 to “just let him go,” prosecutors said. And some time later, Cyril Williams returned and fired a .45-caliber handgun toward the Applebee’s door, fatally wounding Brown as he stepped outside to make a phone call, prosecutors said.

“The defendant was planning to exact his revenge on these police officers that threw him out of the restaurant,” Prince George’s Deputy State’s Attorney Tara Harrison told jurors in her opening statement at Williams’s trial this week. “The defendant did, in fact, exact revenge on Trooper Wesley Brown.”

Williams, 29, is charged with first-degree murder and other related counts in the June 11, 2010, slaying of Brown outside the Applebee’s on Donnell Drive in Forestville. Dozens of his and Brown’s family members, police commanders and uniformed troopers filled a Prince George’s County Circuit courtroom this week.

So far, the trial has been an emotional affair. Patrice Faison, Brown’s sister, tearfully told jurors about how her brother had started a mentoring group for youths in the Seat Pleasant area. Karl Peoples, the Maryland Parole and Probation officer whom Brown was working with that night, talked about how he tried awkwardly to help his wounded partner through the door after he had been shot.

Maryland State Trooper Wesley Brown, 24, is seen in an undated photo provided by the Maryland State Police. (AP)

But William C. Brennan Jr., Williams’s defense attorney, said that although his client might have been thrown out of Applebee’s, prosecutors did not have enough evidence to prove that he came back and shot Brown. He said that prosecutors do not have any DNA or fingerprint evidence and that no unbiased witnesses saw Williams back at the restaurant after he was ejected. The case hinges, Brennan said, on whether jurors believe two jailhouse informants and the man whose gun was used to shoot Brown.

That man, Anthony Milton, 29, has pleaded guilty to being an accessory after the fact to murder and has yet to be sentenced. Brennan said Milton, who prosecutors say was with Williams near the restaurant shortly before the shooting, initially lied to detectives. Brennan said his client had no motive to shoot the trooper.

“Getting thrown out of an Applebee’s does not equate to first-degree murder,” Brennan said.

In the first two days of Williams’s trial, prosecutors focused largely on setting the scene for Brown’s slaying. The 24-year-old state trooper was working security off-duty with Peoples, watching over Applebee’s patrons who were downing drinks and singing karaoke, according to people who were there. At some point, said a woman who was there, someone complained about Williams.

Brown and Peoples took Williams outside, telling him it would be best for him to leave, according to prosecutors’ and Peoples’s accounts. At first, Williams went willingly and agreed to pay his check after a waiter brought it outside, said prosecutors and Peoples. But Peoples said that Williams soon became agitated, gesturing so vigorously that his hands were hitting Brown, then taking a swing at Peoples.

Peoples told jurors that he initially wanted to arrest Williams but let him go at his partner’s suggestion. After he and Brown returned to the restaurant, Peoples testified, he told Brown that they should sometimes make arrests.

Later, Peoples said he heard what sounded like firecrackers and saw his partner stumbling toward the doorway. Brown had been shot.

Two D.C. firefighters and a nurse inside the restaurant performed CPR until an ambulance arrived, but their efforts were in vain. Brown never regained a pulse.

“I’m frustrated,” Peoples said of how he felt that night. “I’m mad. I’m still mad right now.”

Prosecutors said Williams was the shooter. They said he had gotten the .45-caliber handgun that night from Milton, a friend of his. They said Williams went to Milton’s house after his initial confrontation with the officers to pick up the gun, telling his friend, “Remember that forty-five? I need that.”

Williams’s trial is expected to last until Thursday.