Police said Thal, 34, and Gilmore, 40, a long-distance truck driver from Ohio, were involved in the city's drug trade. Authorities have said the pair were shot during an attempt to steal more than $100,000 and 18.5 pounds of cocaine that police found later in Thal's apartment.
The death penalty might have been a difficult hurdle for a trial jury.
Earlier Monday, Donnell Murchison, 35, the other alleged gunman facing the possibility of capital punishment, pleaded guilty to two counts of first-degree murder in a deal in which he was immediately sentenced to two consecutive life prison terms without chance of parole.
And the death penalty had earlier been withdrawn in the charges against Will Hook, 43, the alleged mastermind of the robbery gone awry, and Edward N. Daniels, 44, the alleged third gunman who shot at Thal and Gilmore.
The decision to withdraw the death penalty against Wright was confirmed by defense attorney Gary S. Server, who would have presented mitigating evidence to try to save Wright's life had he been convicted of first-degree murder.
Server's comments followed Murchison's guilty plea before a courtroom closed to all but the defense and prosecution lawyers involved out of "security concerns."
Witness intimidation and retaliation are a daily concern at the city's Criminal Justice Center.
This summer, after it became known that Piazza defendant Langdon Scott had testified for prosecutors in August at a preliminary hearing, Scott was stabbed in an attack in the city prisons.
Scott, 28, also pleaded guilty Monday, to conspiracy, robbery, and burglary in a deal in which he is expected to testify at trial against the remaining defendants.
Judge Jeffrey Minehart set sentencing for Jan. 4 and told Scott he faces up to 60 years in prison.
With the guilty pleas by Murchison and Scott, and another set for Tuesday by Robert Keith, 29, the number of defendants going to trial is now three.
One other defendant, Katoya Jones, 27, pleaded guilty last year and is also expected to testify. Jones lived a floor below Thal's apartment and admitted letting the gunmen through the security door for a cut of the drug money.
It is not known if Murchison's plea involves testifying, although that seems unlikely given that he was sentenced immediately and removed from court.
Besides Keith's guilty plea, Tuesday's court session will include a hearing on a motion by Wright's attorney to suppress the incriminating statement he gave police after he was arrested.
Jury selection for the trial of the remaining three defendants begins Wednesday.
Contact staff writer Joseph A. Slobodzian at 215-854-2985, firstname.lastname@example.org, or @joeslobo on Twitter.