Lecourt's testimony - and the now-famous video of the shooting taken by eight newly installed security cameras mounted on the bus - persuaded a Philadelphia judge Thursday to hold Patterson for trial on attempted murder, conspiracy, and related charges.
Lecourt, 19, testifying under a guilty-plea agreement with the District Attorney's Office, answered questions calmly if almost inaudibly as Patterson avoided looking at him and 14 members of their extended families watched raptly from the gallery.
Patterson, 23, became a fugitive and was arrested Dec. 6 - after the six originally arrested shortly after the incident. All of the others have pleaded guilty and, except for Lecourt, been sentenced to multiyear prison terms.
Questioned by defense attorney Nino V. Tinari, Lecourt said he expects to be sentenced to up to five years in prison when he completes the terms of his plea deal.
Tinari questioned Lecourt at length and argued to Municipal Court Judge Charles Hayden that Lecourt was not credible and there was no independent evidence implicating Patterson.
Under questioning by Assistant District Attorney Ed Jaramillo, Lecourt said he was at home in the 1700 block of North Marshall Street about 5 p.m. on June 18, 2011, when he saw Patterson cross the street from her house, saying she just received a phone call from Penny Chapman, 21.
Lecourt, paternal uncle of Chapman's 2-year-old son, said Patterson was angry after Chapman told her a bus passenger was "bullying her" and "got in her face" after she slapped her son for running in the aisle.
Lecourt testified that he followed Patterson to meet two other cousins and another friend who had a semiautomatic rifle and pistol stashed in the trunk of his car.
Minutes later, as the northbound bus stopped at Seventh Street and Cecil B. Moore Avenue, the video shows a group of people converge on the bus and Lecourt escort Chapman and her young son to safety. Then two men open fire.
Lecourt identified himself and Patterson in the bus video. He said Patterson stood outside the bus yelling for the offending passenger to come out.
"What did you think?" Jaramillo asked.
"Something was going to happen to him," Lecourt replied.
When the passenger didn't get off the bus and the driver began to pull away, Patterson ordered her two armed cousins to "shoot the bus up," Lecourt testified.
Police said nine shots pierced the passenger side of the bus, five exiting the driver's side, but none of the dozen passengers was wounded by the shots or hurt by flying glass.
Contact Joseph A. Slobodzian at 215-854-2985, jslobodzian@phillynews.com, or @joeslobo on Twitter.