Rick Morrocco Williams walked into a Charleston courtroom Tuesday morning and waved at his parents in the front row of pews behind the defendant's table.

His attorney later told jurors during opening statements of his murder trial that Williams' loved ones might have been sitting on the opposite side of the courtroom if he hadn't made a difficult but necessary choice three years ago.

Williams shot both of his roommates, 44-year-old Angie Ferguson and 58-year-old Nathaniel Lonnie, once in the head inside their North Charleston apartment on Dec. 31, 2010.

He did it because he feared for his own life when Lonnie came after him with a sword and Ferguson with a box cutter, Williams' public defender, Beattie Butler, told the jurors.

"His choice was to shoot or to be sliced by a sword," Butler said. "He had a choice whether to live or possibly die ... and Ricky chose to live."

Williams' defense appears unchanged from the first two times he was tried on the two counts of murder. The past proceedings, one in each of the last two years, ended in mistrials, the first after a juror didn't disclose pertinent information, the second when jurors couldn't agree on a verdict.

Williams, 28, who has shaved the scruffy beard and tousled hair he had when he was arrested, faces between 30 years and life in prison on each count if he is convicted.

Butler and 9th Circuit Assistant Solicitor Greg Voigt, who is prosecuting Williams with Assistant Solicitor Stephanie Linder, set the groundwork for their cases during the opening statements.

Voigt indicated that jurors likely won't see much physical evidence because the shooter's identity isn't in question. They also will hear witness testimony that will sometimes conflict, Voigt said.

Williams is expected to take the stand, as he has done in the past, during the trial that should last two or three days in Judge J.C. Nicholson's courtroom.

Jurors also will watch a North Charleston police video that showed the victims' bodies in the living room of their Durant Avenue home. They were found there about three days after they were killed in the early morning of New Year's Eve 2010.

Williams was arrested soon after the discovery, but he waived his right to remain silent and instead told police his story.

He had gotten into an argument with the couple who had been drinking a grain alcohol that Butler referred to as moonshine. The dispute was about a dog.

At some point, Lonnie was offended by Williams' cursing, and he told Williams to get out of the house because he was a "freeloader" who didn't pay rent, Butler said.

Before Williams left, he used a baseball bat to smash every window and the headlights of Lonnie's minivan, police said.

Williams later returned to retrieve his belongings, Butler said. Lonnie wasn't there when he returned, so Ferguson let him inside, the attorney said.

Lonnie became enraged when he came back and found Williams in the home, according to Butler.

Williams was cornered, Butler said, so when Lonnie came after him with the sword, he fired. Angry, Ferguson lunged at Williams with a box cutter, Butler said. He shot her too.

Butler told jurors that Williams' response was imperfect but reasonable.

Voigt said Williams' conduct was calculated when he walked into the home and shot the couple.

"Rick Williams is somebody who, in another context, might deserve sympathy," Voigt said. "But sympathy for him has no place."

Reach Andrew Knapp at 937-5414 or twitter.com/offlede.