MILFORD, Pa. – Cpl. Bryon Dickson spent the last moments of his life lying alone on a sidewalk outside the state police barracks where he worked, trying to lift his head, moving his eyes back and forth, and making gurgling sounds as a lung filled with blood.

"Help me," he mouthed to the police dispatcher who found him.

His killer, meanwhile, remained hidden in darkness.

With the depiction of that haunting scene and dramatic testimony from the dispatcher, the prosecution opened its case in the death-penalty trial of Eric Frein.

On Sept. 12, 2014, Dickson went to the Blooming Grove barracks "to engage in another day of service on behalf of all of us," Pike County First Assistant District Attorney Bruce DeSarro said in his opening statement.

That same day, DeSarro said, Frein was on his computer doing "research about how police respond to shootings."

Frein, 33, is charged with first-degree murder, terrorism, and other crimes in the death of Dickson and the shooting of Trooper Alex Douglass at the barracks that night. Frein, of Canadensis, eluded capture during a 48-day manhunt in the Poconos, drawing national attention and more than 1,000 law enforcement officers to Pike and Monroe Counties.

In his brief opening statement, Frein's defense attorney called the deadly ambush and standoff "a tragedy I don't know how this county will ever recover from."

The lawyer, Michael Weinstein, said Frein would not testify, and he did not seek to explain or rebut accounts of the alleged crimes. He simply asked the jury to remember that Frein must be presumed innocent unless proved otherwise.

"That cloak of innocence remains on that defendant unless and until the commonwealth can remove it," Weinstein said. "Hold them to that responsibility."

The trial is expected to last five weeks in Pike County's historic courthouse. A jury from Chester County will determine Frein's fate and will be sequestered here for five nights a week.

Large areas outside the courthouse were roped off or had barriers around them Tuesday morning to accommodate media coverage and attention far from typical in the small town of Milford. The county raised taxes this year to pay for the trial, for which commissioners budgeted $250,000.

Churches and some homes near the courthouse displayed blue ribbons – a sign of support for police. Inside the nearly full courtroom, many seated in the gallery wore blue ribbons fastened to their shirts. Friends and family members of the two troopers were in attendance, as were members of the state police, including Lt. Col. George Bivens. Bivens was the public face of the manhunt for Frein, regularly briefing reporters on the investigation.

Frein, dressed in a suit and tie and wearing glasses, looked at his parents and sister as he entered the courtroom. He sat quietly between his lawyers, looking intently at prosecutors' slide show during opening arguments.

DeSarro's statement to jurors detailed the shooting and the manhunt, complete with a preview of the photos, videos, and other evidence that will be shown. Among the prosecution witnesses will be Douglass. DeSarro said Douglass still has difficulty walking due to injuries from the shooting.

Prosecutors played a recording Tuesday of a dispatcher's phone call that caught the loud popping noise of the gunshot that felled Dickson.

The dispatcher, Nicole Palmer, testified that she went to the door after hearing the noise. Moments earlier, Dickson had walked out of the barracks and told her, "Have a good night," she said. She found him on the sidewalk, mouthing, "Help me."

Crying as she recounted the events of that night, she said she dialed 911 from the barracks lobby -- but it was only an internal phone line that rang at her own empty desk. She returned to the doorway to ask Dickson what happened.

"He mumbled to me, 'I've been shot; drag me inside,' " Palmer said. "I looked at him and told him, 'I can't.' And I came back in. ... I was afraid for my life."

After that, she said, she saw Douglass be shot and crawl into the lobby.

Jurors also saw Dickson fall to the ground and Douglass, who had walked up from a lower parking lot when he heard the gunshots, crawl into the lobby as he bled. Prosecutors played surveillance video of the shooting in court Tuesday afternoon.

Palmer described panicked moments inside the barracks as she notified the troopers of the shooting. At one point after an ambulance arrived, she said, she heard someone say about Dickson, "He's gone."

From the spot on the sidewalk where Dickson lay dying, DeSarro told jurors, he would have seen two flagpoles, with the U.S. and Pennsylvania flags, and "a rural night sky, representing the heavens above."

He portrayed Frein, meanwhile, as a man who wanted to start a revolution by shooting police officers. DeSarro showed photos of Frein's bedroom, at his parents' home, where police found guns, packing lists, and materials to make explosives. He walked jurors through the evidence found while Frein was on the run, including a journal entry left at a campsite describing the shooting in graphic detail.

Frein's lawyer told jurors to pay close attention to Frein's demeanor during a video-recorded interview with police on the night of his capture. Weinstein had argued before the trial that the recording should be excluded from evidence, but after Judge Gregory Chelak decided Monday afternoon to permit it, Weinstein told jurors it would be useful for them to get to know Frein.

"It was a candid conversation," Weinstein said. "It will give you a chance to meet Eric. It will give you a chance to see what he's like."

The trial is to resume Wednesday morning.