Because Oeax was angry at the Greeks for killing Palamedes at Troy, he falsely told Clytemnestra about Agamemnon bringing back Cassandra, a Trojan concubine, which led to Clytemnestra plotting to kill Agamemnon.[5] Later, Oeax tried to banish Orestes after the latter murdered his mother Clytemnestra.[6] Ultimately, Oeax and his brother Nausimedon were killed by Pylades after helping Aegisthus in his fight with Orestes.[7]
Euripides, The Complete Greek Drama, edited by Whitney J. Oates and Eugene O'Neill, Jr. in two volumes. 2. Orestes, translated by Robert Potter. New York. Random House. 1938. Online version at the Perseus Digital Library.
Hard, Robin, The Routledge Handbook of Greek Mythology: Based on H.J. Rose's "Handbook of Greek Mythology", Psychology Press, 2004, ISBN9780415186360. Google Books