Achilles's best friend murdered by Hector
Patroclus of Bourges died in 576.
Patroclus of Bourges was born in 496.
Patroclus of Troyes died in 259.
Achilles friends were Patroclus only Patroclus from the illiad
Patroclus (in the Iliad) was killed by Hector - who had mistaken him for Achilles (Patroclus had borrowed Achilles' armour). So if the question is: 'Who did not kill Patroclus?' the answer is: everybody except Hector (Aeneas, Troilus, Sarpedon, Calchas, Hecuba .....).
Patroclus is killed by Hector, the greatest of the Trojans.
Patroclus is the son of Menoetius. Greek legend.
Achilles sought revenge for the death of Patroclus. The death of Patroclus was Achilles' main motivation for his killing of Hector.
Patroclus is the reason why Achilles desired to kill Hector.
Patroclus fought on the Greek side.
I don't think Achilles stole anything from Patroclus. Patroclus stole Achilles armor and war it into battle. The Trojans thought he was Achilles and killed him.
Patroclus was killed by Zeus because Patroclus killed his son Sarpedon. Zeus had Apollo wound him badly which made it easy for Hector to finish him off.