As the second trial of two men charged with a fatal robbery and stabbing began yesterday, a pair of witnesses testified about the death of Michael Hixson in 2003 in Mellon Square Park, Downtown.

But defense lawyers, in harsh cross-examination, questioned the motives and sometimes conflicting stories of the two witnesses: the alleged third co-conspirator, Marvin Harpool, 22, who took a plea deal from prosecutors in exchange for his testimony; and a 44-year-old woman who caused a mistrial in July when she unexpectedly identified one of the defendants from the stand.

Leonard Ray "Cornbread" Anthony, 25, and Kristopher E. "Dyce" Garner, 25, are standing trial on charges of homicide, robbery and conspiracy.

In July, the woman -- whose name prosecutors asked to be withheld out of fear for her safety -- was called to testify to what she saw the night of Sept. 12, 2003. She was not expected to identify either of the defendants. But before she entered the courtroom, she spotted Mr. Anthony in the hallway.

In July, the woman said she recognized Mr. Anthony as the man who stabbed Mr. Hixson, 38, of McKeesport, even though the killer was wearing a bandana over most of his face. Senior Common Pleas Judge John K. Reilly declared a mistrial then because of the "surprise evidence."

The woman repeated her identification of Mr. Anthony yesterday.

"I could identify him from his eyes, because there was no remorse in them," she said.

Mr. Harpool, who has agreed to plead guilty to third-degree murder in exchange for his testimony, said that after Mr. Hixson declined to buy drugs from Mr. Anthony, Mr. Anthony punched him. Mr. Hixson tried to run away, but Mr. Garner tripped him, Mr. Harpool said.

Mr. Harpool said he and Mr. Garner started punching and kicking Mr. Hixson before Mr. Anthony stabbed Mr. Hixson several times with a 10-inch knife. The men took $20 and a cell phone from Mr. Hixson, who later died of his wounds.

Defense lawyers Michael Worgle and Owen M. Seman challenged Mr. Harpool on conflicting statements he gave to investigators after he was arrested in 2005. At one point, Mr. Harpool told police he ran away as soon as he saw Mr. Anthony pull out the knife.

But he testified yesterday that he was telling the truth when he told police he witnessed the stabbing.

"My first statement was the best statement because it was more near the date of it happening," Mr. Harpool said. "After that, I tried to forget about it."

The prosecution will continue presenting its case today.