Murchison called Shuler, who owned the now-closed Plush nightclub at Eight and Callowhill Streets - Thal, a party planner, also worked there as a manager - the "inside guy" who gave Hook information on the amount of drugs and cash police later found in Thal's apartment.
Shuler could not be reached for comment but his attorney, Tariq Karim El-Shabazz, denounced Murchison's testimony.
El-Shabazz said Shuler cooperated and agreed to be questioned by police and prosecutors about the double murder.
"It's been two years and Darryl Shuler's name has never been on any arrest warrant and he's not sitting there with the other [defendants]," El-Shabazz said. "That should give you an idea of the weight of that testimony."
El-Shabazz said there is "not one scintilla of evidence" linking Shuler to the robbery plot that ended with Thal's and Gilmore's murders.
Assistant District Attorney Jennifer Selber, who is prosecuting the case with Carlos Vega, said she could not comment on Murchison's testimony about Shuler and his alleged role in the scheme.
Prosecution and defense lawyers have been barred from talking with reporters by a gag order imposed by Judge Jeffrey P. Minehart.
Murchison pleaded guilty to two counts of murder and was sentenced to two consecutive life terms on Nov. 7, as jury selection was beginning in the Common Pleas Court trial.
His plea agreement, as outlined to the jury by Vega, includes moving him to a federal prison out of Pennsylvania to serve his sentence and protection for his mother, two-year-old daughter and her 28-year-old mother.
"My family is being threatened," Murchison testified. "I don't want to put my family in harm's way for something I have done."
But Murchison testified in name only. He actually refused to testify until, ultimately, he reluctantly gave one-word answers as Vega read his two statements to detectives aloud in court.
"I kept my promise, I'm taking care of your little girl," Vega reminded Murchison, referring to the protection for him and his family.
Thal's mother and sister left the courtroom as Murchison's statement got to the part where he described the murders and what he called Thal's willing role in the scheme that ended in her death.
Murchison will continue being questioned through the afternoon by Hook's lawyer, Christopher D. Warren, who opened his cross-examination with questions soaked with sarcasm.
"Who's out on the street that you might be afraid of, sir?" Warren asked, referring to the arrests of eight people in the slayings, four of whom have already pleaded guilty.
Murchison insisted that the three defendants "have people everywhere who are willing to kill for them."
Thal, 34, a party planner, and Gilmore, 40, a long-distance truck driver based in Ohio, were shot dead in the hallway outside her posh seventh-floor apartment. The gunmen confronted Thal and Gilmore, Gilmore tried to flee and the gunmen opened fire.
The gunmen then fled, leaving behind what they came for: more than $100,000 in cash and 8-1/2 pounds of cocaine that police later found in Thal's apartment.
Contact staff writer Joseph A. Slobodzian at 215-854-2985, firstname.lastname@example.org, or @joeslobo on Twitter.
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