The informant, Frederick Collins, was charged last month with screaming profanities at an Allegheny County judge presiding over his unrelated case on witness intimidation and other charges.
Collins and another informant have told prosecutors Cheron Shelton and Robert Thomas told them they were trying to kill a man during the March 2016 shootings in Wilkinsburg. The target was wounded but survived, but five others — including a pregnant woman — were slain.
Police say Thomas opened fire on one side of the backyard while Shelton used an assault rifle to gun them down as they ran onto a porch for safety.
The Pittsburgh Post-Gazette (http://bit.ly/2sDeUzP ) says defense attorneys now plan to challenge evidence seized with search warrants based on information Collins provided.