Raleigh, N.C. — Samuel James Cooper's confession to fatally shooting five men and the methods investigators used to get it were the focus of a second day of testimony in what's expected to be a long capital murder trial.

Cooper, 33, is on trial facing five first-degree murder charges in the deaths of Ossama "Sam" Haj-Hussein, LeRoy Jernigan, Timothy Barnwell, Ricky High and Tariq Hussain – all were killed during a period spanning more than a year in 2006 and 2007.

Garner police arrested Cooper Nov. 21, 2007, following a bank robbery and a subsequent police chase that captured the attention of Raleigh police investigators working the slayings at the time.

Sgt. Kevin Carswell, a supervisor with one of the Raleigh Police Department's homicide squads, testified Tuesday afternoon that investigators at the time had few leads in High's Oct. 12, 2007, shooting and that of Hussain's two days later.

Cooper, they said, matched the general description of a suspect in the cases and that they immediately became interested in the Garner robbery when they learned police recovered a 9 mm Ruger handgun that Cooper dropped during an attempt to flee police.

A preliminary analysis of the gun on Nov. 22 connected the weapon to all five cases, Carswell testified.

"It kind of took me back for a second," he said. "I wanted to be sure. I said, 'Are you 100 percent sure that these are connected?'"

Carswell immediately notified his supervisor, he said, and started alerting detectives looking at Haj-Hussein's May 12, 2006, death, Jernigan's June 3, 2006, death and Barnwell's April 27, 2007, death.

Retired Raleigh police homicide investigator George Passley, who was the lead detective at the time in High's case, also testified Tuesday about trying to interview Cooper four times about the cases.

It wasn't until Nov. 26, five days after the bank robbery, that Cooper agreed to talk about them.

By that time, police had already arrested and charged Cooper's father, Samuel James Cooper Sr. with possession of a weapon by a felon, Passley said. Cooper agreed to talk about the shootings if his father was released and the charge dropped.

Defense attorneys questioned Passley at length about the timing and circumstances surrounding the elder Cooper's arrest. During a pre-trial hearing last year, they sought to have Cooper's confession suppressed, saying he was coerced into admitting to the crimes.

Passley said investigators searching the Cooper home found a .380 automatic Cole pistol that belonged to the younger Cooper that his father had hidden – grounds for a charge.

But an arrest wasn't made until two days later after Samuel Cooper Jr. became concerned about what would happen to his father. He saw his father taken into custody and asked to speak for a fifth time to Passley.

"Samuel James Cooper said, 'I'll tell you everything, just let Dad go,'" Passley testified.

What ultimately followed in the early hours of Nov. 26 was a six-hour interview in which Cooper confessed in detail to the homicides, confessed to at least 17 other robberies and admitted to robbing businesses and banks "to make money."

Jurors heard an hourlong except of that interview Tuesday. (Read the transcript.)

"He said that he wasn't into street stick-ups or carjackings," Passley said, adding that Cooper said he only targeted places where he thought there was money.

Robbery, prosecutors have said, was Cooper's motive in four of the five slayings.

Defense attorneys pointed out that Cooper committed other robberies and that not all of them ended in death. Cooper had told police that he tried to stay calm during robberies and that shooting his victims wasn't his intent.

When asked about Barnwell – prosecutors say Cooper handcuffed and hogtied him while searching his apartment for money and drugs, then shot him after he managed to jump over his second-floor balcony – Cooper said he only shot him when he tried to get away.

"He said his instinct kicked in," Passley said. "So, he shot him."

Passley said Cooper admitted to going to his car, getting a towel and then returning to clean off fingerprints inside Barnwell's apartment. He also removed the cuffs from his hands, then left.

The defense has admitted that Cooper committed the crimes but said the issue in the case is whether he acted with premeditation and deliberation.

In opening statements Monday, defense attorney Stephen Freedman said Cooper suffers from a diminished capacity from years of physical abuse at his father's hands, which affects his ability to think clearly, particularly in moments of stress. (Read more about opening statements in the trial.)

On redirect Tuesday, prosecutors asked Passley about Cooper's demeanor during the confession.

Cooper, he said, would sometimes laugh before he would answer a question.

"He was very relaxed. The conversation was as we're talking now – a very normal tone," Passley said. "There was no stress between me and Sam. Very civil."