Donte Johnson, who had been expected to plead guilty Friday in the rape and murder of 20-year-old Sabina Rose O'Donnell, instead hired a new lawyer this week to review his case.

Douglas L. Dolfman, Johnson's new attorney, asked Common Pleas Court Judge Benjamin Lerner on Friday to postpone Johnson's next court appearance.

"It comes down to getting a second opinion," Dolfman said after Friday's court proceedings. Johnson "and his mother were just not very comfortable with what's going on in the case."

Johnson, 18, faces life in prison in the death of O'Donnell, who was strangled June 2 in a vacant lot behind the apartment where she lived with her stepfather on the edge of Northern Liberties.

Johnson, who was arrested two weeks after O'Donnell's death, has confessed to the brutal killing, police said. Investigators have also linked DNA evidence found on O'Donnell's body to Johnson.

Members of O'Donnell's family knew there would likely be painful details of the killing discussed in court if Johnson pleaded guilty, but had planned to attend. On Wednesday, they learned of the change in plans.

"It's worse than frustrating," said Mark Rounds, O'Donnell's stepfather. "I've been gearing up for this for two weeks."

Dolfman, who made his first appearance as Johnson's lawyer in court Friday, said he needed time to review the evidence in the case and to meet with Johnson. Johnson's next court appearance has been scheduled for Jan. 5.

"It's difficult for a mother to have her 18-year-old kid throw his life away on a life in prison," he said after court. "If we have to go to trial, we'll go to trial."

He added that Johnson was having trouble coming to terms with the reality of a life sentence.

"He doesn't yet understand completely what he's facing," he said.

Assistant District Attorney Richard Sax, who is prosecuting the case, said it was "always a possibility" that the case could go to trial.

"If [Johnson] wants his trial, which he is absolutely entitled to, we're prepared for that as well," he said.

O'Donnell's killing, Sax said, deeply affected the residents of the Northern Liberties neighborhood where she worked as a waitress and spent time with friends. Her family continues to grieve, he said.

"It's devastating every morning," he said. "And it always will be."

Contact staff writer Allison Steele at 215-854-2641 or asteele@phillynews.com.