In vengeance for the affair, Atreus killed Thyestes' sons and served them to him at a banquet.
So when Pelopia, who at the time stayed in Sicyon at the court of king Thesprotus, came to the bank of a river to wash her clothes that had been stained with blood during a sacrificial rite, Thyestes, covering his face, attacked and raped her.
As Pelopia had been impregnated by her father Thyestes, she soon gave birth to Aegisthus and abandoned him.
When he already entered adulthood, Thyestes was captured by Agamemnon and Menelaus at Delphi and brought to Atreus, who sent Aegisthus to kill him.
Upon recognizing Thyestes and the fact that he was the rapist, Pelopia stabbed herself with her father's sword.