Peter Atem, 32, was convicted Friday of first-degree murder and related charges.
Investigators say in February 2015, a day before the fatal stabbing, 25-year-old Danny Vazquez tried to pull a chair out from under Atem.
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Following the prank, investigators say Atem told Vazquez, "I'm going to get you for that."
The following day, while working at the MOPAC Rendering Plant in Franconia Township, a witness saw Atem in a physical confrontation with Vazquez.
A short time later, investigators say the witness heard screaming and saw Atem stabbing Vazquez.
The witness tried to help the victim, who became unresponsive.
Vazquez was taken to Abington-Lansdale Hospital where he was pronounced dead.